Use substitution to solve. Rearrange the second equation so that it is equal to y. Plug in the value for y into the first equation.
3x + y = 37
y = 37 - 3x
2x + 2y = 42
2x + 2(37 - 3x) = 42
2x + 74 - 6x = 42
74 - 4x = 42
-4x = -32
x = 8
Now that you have the value for x, solve for y using one of the equations. I will use the first equation, but you can use the other one and still get the right answer.