1）x÷14/15=1/7
x=(1/7)*(14/15)=14/(7*15)=2/15
2)(1-5/8)x=10
(8/8-5/8)x=10
(3/8)x=10
x=10/(3/8)=10*8/3=80/3
3）1/5+4x=4/5
4x=4/5-1/5
4x=3/5
x=(3/5)/4=3/20