5/12X+1/4=8/21
5/12X=8/21-1/4
5/12X=11/84
X=11/84÷5/12
X=11/35
1/5÷X=6/25
X=1/5÷6/25
X=5/6第2题打错了是1/5*8÷X=6/251/5*8÷X=6/258/5÷X=6/25X=8/5÷6/25X=20/3