Use elimination to find both values.
Subtract the second equation from the first equation
x + 15y = 40
- x + 10y = 30
————————
5y = 10
y = 2
Plug in the value for y into one of the equations. I’m going to put it in the second equation.
x + 10(2) = 30
x + 20 = 30
x = 10
x = 10
y = 2