You can multiply the first equation by 3 and get: 12x + 9y = 60
Then multiply the second equation by 4 and get: 12x + 8y = 48
Now because in both equations there is a 12x, you can subtract both the equations, eliminating the x meaning you are left with: y= 12.
Then, if you would like to find out the x value, you can substitute y=12 into any of the 2 equations, and then solve. Hope that helps