| SBowman's final answer is correct but I have two comments:
First, the following line is wrong:
40x - 21 / 35 = 0
It should be
40x/35 - 21/35=0
Second, the following method is much simpler:
x/(7/8)=(3/5)
multiply both sides by (7/8)
x=(3/5)*(7/8)
simplify
x=21/40 |