ANSWER
x = 15, y = 30
EXPLANATION
We want to solve the system of equations by substitution method.
We have that:
y = x + 15
y = 2x
Substitute the value of y in the second equation into the first:
=> 2x = x + 15
Collect like terms:
2x - x = 15
x = 15
Recall that:
y = 2x
=> y = 2(15)
y = 30
The solution to the system of equations is: x = 15, y = 30
