Answer:
Use the solution below as a guide.
x = 45
Explanation:
Your question is not clear, but assuming the Question is 1x - y = 30, when y = 15
Therefore,
Take this 1x - y = 30 .............. eqn 1
When y = 15, Substitute for Y in eqn1
1x - 15 = 30
1x = 45
x = 45