Hello from MrBillDoesMath!
Answer: x = 16
Discussion:
We are told that
y/x = 3/4
If y = 12, then
12/x = 3/4. Multiply both sides by "x" :
(12/x) * x = (3/4) * x =>
12 = (3/4) *x. Multiply both sides by (4/3)
12* (4/3) = (3/4) * (4/3) * x =>
48/3 = x =>
x = 16
Thank you,
MrB