计算,能简算的要简算.我要算式和答案
1个回答

5/7÷13/5+2/7*5/13

=5/7*5/13+2/7*5/13

=(5/7+2/7)*5/13

=1*5/13

=5/13

2-9/34÷6/17-1/4

=2-9/34*17/6-1/4

=2-3/4-1/4

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

=2-1

=1

5*(1/20+2/15)-2/3

=5*1/20+5*2/15-2/3

=1/4+2/3-1/3

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

=1/4+1/3

=7/12

〔1/2-(2/3-2/5)〕÷7/10

=(1/2-2/3+2/5)÷7/10

=1/2*10/7-2/3*10/7+2/5*10/7

=5/7-20/21+4/7

=5/7+4/7-20/21

=1-20/21

=1/20