You plug the x and y values back into both equations. If both come out to be true statements ie. 4=4, 7=7 your answer is correct. If one or both of the equations turn into false statements, the ordered pair is not the solution to the system.
Subtract 25 and 10 which gives you 15 subtract 5/8 and 1/8 since they have common denominators. You get 15 1/2 when you simplify 15 4/8 in which 4/8 is the same thing as 1/2.