(-9/10-15/16).(5/12-11/15-7/20)

5/14.1/3.-4/15:5/7

-3/5+28/5.(43/56+5/24-21/63)

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50+51+52+53+54+56+57+58+59+60+61+62+63+64+65+66+67+68+69+70=?

Thực hiện phép tính sau:

a)(9/10—15/16)(5/12—11/15—7/20)

b)—3/5+28/5(43/56+5/24—21/63)

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50=?

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50.

Làm giúp mình một vài con toán này với: Tính bằng phương pháp hợp lí nhất nhá

a) (9/10 - 15/16) * ( 5/12 - 11/15 -7/20 ) 

b) -3/5 + 28/5 * ( 43/56 + 5/24 - 21/63)

c) ( 1 +1/2 ) * ( 1 * 1/3 ) * ( 1+1/4 ) *...* ( 1* 1/99 )

a) \(\left(\frac{9}{10}-\frac{15}{16}\right).\left(\frac{5}{12}-\frac{11}{15}-\frac{7}{20}\right)\)

B) \(\frac{-3}{5}+\frac{28}{5}.\left(\frac{43}{56}+\frac{5}{24}-\frac{21}{63}\right)\)

thực hiện phép tính

1 + 3 + 5 +7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23 + 25 + 27 + 29 + 2 + 4 + 6 + 8 + 12 + 14 + 16 + 18 + 20 + 22 + 24 + 26 + 28 + 30 =???