Dọc theo chiều dài, ta trồng được:

\(5.5 : \frac{1}{4} = 22\) (khóm hoa)

Dọc theo chiều rộng, ta trồng được:

\(3 , 75 : \frac{1}{4} = 15\) (khóm hoa)

Như vậy, số khóm hoa trồng được dọc theo hai cạnh của mảnh vườn là:

\(\left[\right. \left(\right. 22 + 15 \left.\right) . 2 \left]\right. - 4 = 70\) (khóm hoa)

Đáp số: 70 khóm hoa

a) 1/5 + 4/5 : x = 0,75

1/5 + 4/5 : x = 3/4

4/5 : x = 3/4 - 1/5

4/5 : x = 11/20

x = 4/5 : 11/20

x = 16/11

b) x + 1/2 = 1 - x

2x = 1 - 1/2

2x = 1/2

x = 1/4

a) (2/3) . (5/4) - (3/4) . (2/3)

= (2/3) . (5/4 - 3/4)

= (2/3) . (2/4)

= (2/3) . (1/2)

= 1/3

b) 2 . (-3/2)^2 - 7/2

= 2 . (9/4) - 7/2

= 18/4 - 14/4

= 4/4 = 1

c) -(3/4) . (5.3/13 + 36/13)

= -(3/4) . ((15 + 36)/13)

= -(3/4) . (51/13)

= -(3.51)/(4.13)

= -153/52 ≈ -2.94

a)
\(\left(\right. 1 / 2 + 1.5 \left.\right) . x = 1 / 5\)
\(\Rightarrow 2. x = 1 / 5\)
\(\Rightarrow x = 1 / 5 : 2 = 1 / 10\)

b)
\(\left(\right. - 13 / 5 + x \left.\right) : \left(\right. 12 / 13 \left.\right) = 21 / 6\)
\(\Rightarrow - 8 / 5 + x = \left(\right. 13 / 6 \left.\right) . \left(\right. 12 / 13 \left.\right)\)
\(\Rightarrow - 8 / 5 + x = 2\)
\(\Rightarrow x = 2 + 8 / 5 = 18 / 5 = 33 / 5\)

c)
\(\left(\right. x : 21 / 3 \left.\right) .1 / 7 = - 3 / 8\)
\(\Rightarrow \left(\right. x : \left(\right. 7 / 3 \left.\right) \left.\right) .1 / 7 = - 3 / 8\)
\(\Rightarrow x . \left(\right. 3 / 7 \left.\right) .1 / 7 = - 3 / 8\)
\(\Rightarrow x = \left(\right. - 3 / 8 \left.\right) : \left(\right. 3 / 49 \left.\right) = \left(\right. - 3 / 8 \left.\right) . \left(\right. 49 / 3 \left.\right)\)
\(\Rightarrow x = - 147 / 24 = - 61 / 8\)

d)
\(- 4 / 7. x + 7 / 5 = 1 / 8 : \left(\right. - 12 / 3 \left.\right)\)
\(\Rightarrow - 4 / 7. x + 7 / 5 = 1 / 8. \left(\right. - 3 / 5 \left.\right) = - 3 / 40\)
\(\Rightarrow - 4 / 7. x = - 3 / 40 - 7 / 5 = - 3 / 40 - 56 / 40 = - 59 / 40\)
\(\Rightarrow x = \left(\right. - 59 / 40 \left.\right) : \left(\right. - 4 / 7 \left.\right) = \left(\right. - 59 / 40 \left.\right) . \left(\right. - 7 / 4 \left.\right) = 413 / 160 = 293 / 160\)

a) x + 1/3 = 1/2 - 5/6

=> x = (1/2 - 5/6) - 1/3

=> x = (-1/3) - 1/3

=> x = -2/3

b) 3/8 + 5/8 - 1/5 - x = 1/5

=> 1 - 1/5 - x = 1/5

=> x = 1 - 1/5 - 1/5

=> x = 1 - 2/5

=> x = 3/5

a) x = 7 - 2/5 + 1.62

= (7 - 2/5) + 1.62

= 6 3/5 + 1.62

= 6.6 + 1.62 = 8.22

b) x = 4 3/5 + 1/5 - 1/2

= 4 + (3/5 + 1/5 - 1/2)

= 4 + (4/5 - 1/2)

= 4 + (8/10 - 5/10)

= 4 + 3/10 = 4 3/10

c) 2x - x = 3/5 + 4/7

=> x = 3/5 + 4/7

=> x = (21 + 20) / 35 = 41/35 = 1 6/35

d) x = 3 1/2 - 5/7 + 1/13 - 0.25

x = 2 223/364

A = [2/7 . (1/4 - 1/3)] : [2/7 . (1/3 - 2/5)]

= (1/4 - 1/3) : (1/3 - 2/5)

= (-1/12) : (-1/15)

= (-1/12) . (-15/1)

= 15/12 = 1 1/4

Tử số: 3/4 . (1/5 - 2/7 - 1/3 + 2/7)

= 3/4 . (1/5 - 1/3)

= 3/4 . (-2/15) = -6/60 = -1/10

= 1/5 . (13/21) - 1/3 . (13/21)

= (13/105) - (13/63)

= (13 . 3 - 13 . 5) / 315

= (39 - 65)/315 = -26/315

= 1 11/52

a)A = 3/5 . 6/7 + 3/7 . 3/5 - 2/3 . 3/5

= 3/5 . (6/7 + 3/7 - 2/7)

= 3/5 . 7/7

= 3/5

b)B = (-13 . 2/5 + (-2/9 . 2/5 + 2/5 . 11/9) . 5/2)

= (-13 - 2/9 + 11/9) . 2/5 . 5/2

= (-13 + (11/9 - 2/9)) = -13 + 9/9 = -13 + 1

= -12

c)C = (-4/5 + 5/7) . 3/2 + (-1/5 + 2/7) . 3/2

= ((-4/5 + -1/5) + (5/7 + 2/7)) . 3/2

= (-5/5 + 7/7) . 3/2

= ( -1 + 1 ) . 3/2 = 0 . 3/2 = 0

d)D = 4/9 : (1/15 - 10/15) + 4/9 : (2/22 - 5/22)

= 4/9 : (-9/15) + 4/9 : (-3/22)

= 4/9 . (-15/9) + 4/9 . (-22/3)

= -60/81 + (-88/27)

= (-20/27 - 88/27) = -108/27 = -4

a) P = 2/3 + 1/4 + 3/5 - 7/45 + 5/9 + 1/12 + 1/35

P = (2/3 + 5/9) + (1/4 + 1/12) + (3/5 + 1/35) - 7/45

P=(6/9 + 5/9) + (3/12 + 1/12 ) + ( 21/35 + 1/35) - 7/45

P= 11/9 + 1/3 + 22/35 - 7/45

P=14/9 + 22/35 - 7/45

P= (490/315 + 198/315 - 49/315)

P = 71/35

b) Q= 89/20 - 123/20 - 79/20

Q = (89 - 123 - 79)/20

Q = (-113)/20

a) A= (5/15 - 8/15- 1/7) + (10/15 - 7/15+ 8/7)

A= (−1/5−1/7) + (1/5+8/7)

A=−12/35+47/35=35/35= 1

b) B = 1/4 + 3/5 - (1/8 - 2/5 + 5/4)

B= 17/20 - 39/40

B= 34/40 - 39/40 = -5/40 = -1/8