Question

x-15-1/5(x-15)=15+1/5(x-15) .15*3/5*21+15*4/7*21怎么解

Answer 1

x-15-1/5(x-15)=15+1/5(x-15)

(x-15)-1/5(x-15)=15+1/5(x-15)

4/5(x-15)=15+1/5(x-15)

3/5(x-15)=15

方程两边同乘以5/3得

x-15=25

x=40

15*3/5*21+15*4/7*21

=3*3*21+15*4*3

=3*3*21+3*5*4*3

=3*3*(21+20)

=9*41

=369