QUY TẮC ⇒ TÍNH ĐƯỢC KẾT QUẢ BẰNG BAO NHIÊU RỒI CỘNG THÊM 100.

40 + 40 = 180 

20

40

60

80

100

120

kb minh nha

10+10=20

20+20=40

30+30=60

40+40=80

50+50=100

60+60=120

a) 90 – ( 30 – 20) = 90 – 10

                   = 80

90 – 30 – 20 = 60 - 20

                  = 40

b) 100 – (60 + 10) = 100 – 70

                   = 30

100 - 60 + 10 = 40 + 10

                   = 50

c) 135 – (30 + 5) = 135 – 35

                   = 100

135 – 30 – 5 = 105 – 5

                   = 100

d) 70 + (40 – 10) = 70 + 30

                   = 100

70 + 40 – 10 = 110 -10

                   = 100

nguuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu

x là 10

20+30+40+x=100

90+x=100

x=100-90 

x=10

\(x+40=20+30\)

\(x+40=50\)

           \(x=50-40\)

           \(x=10\)

k mk nha

10 nha

10 + 30 + 70 + 20 + 40 x 0

= 10 + 30 + 70 + 20 + 0

= 130

Tk mk nha!

10 + 30 +70 + 20 + 40 x 0 = 0

=10+10+10-20=20+10-20=30-20=10

=260

Ủng hộ nhé

90 + 90 + 10 + 20 + 30 + 40 + 50 + 60 - 120

= (90 + 10) + 90 + (20 + 30 + 50) + (40 + 60) - 120

= 100 + 90 + 100 + 100 - 120

= 390 - 120

= 270

5 - 10 + 15 - 20 + 25 - 30 + 35 - 40 + 45

= 45 - 40 + 35 - 30 + 25 - 20 + 15 - 10 + 5

= (45 - 40) + (35 - 30) + (25 - 20) + (15 - 10) + 5

= 5 + 5 + 5 + 5 + 5

= 25

25

k cho mk nha