(94/3)*(83/2)-(34/3)*(83/2)-4 1.5*20 4 1.5=83/2

=(83/2)*(94/3-34/3-20)

=0

7/ 12 minus 9/20+1/30 minus 13/42+ 15/56 minus17/72+19.

7/ 12-9/20+ 1 1/30- 13/42+ 15/56- 17/72+ 19/90

=( 1/3+ 1/4)-( 1/4+ 1/5)+( 1/5+ 1/6)-( 1/6+ 1/7)+( 1/7+ 1/8)-( 1/8+ 1/9)+( 1/9+ 1/ 10)

= 1/3+ 1/ 10

= 13/30

The first problem is to use the distribution law, that is, to merge similar items.

The second question uses the column method. 7/ 12= 1/3+ 1/4

1 1/30= 1/5+ 1/6……

∴ Original formula =1/3+1/4-1/5+1/5+1/6-1/6-65538.

= 1/3+ 1/ 10

= 13/30

Turn a fake score into a substitute score

Divide first and then calculate.