This problem looks pretty intimidating with all those variables. In fact, you might be about to cry "POOD" and go on to the next problem. That might not be a bad idea but before you skip the question, pull out those MADSPM rules.For the first equation, you can use the Divide-Subtract Rule: ayax​=ax−y=a10. Inother words, the first equation tells you that x−y=10.For the second equation, you can use the Power-Multiply Rule: (ay)3=a3y=ax. So, that means that 3y=x.Now, it's time to substitute: x−y=3y−y=10. So, 2y=10 and y=5. Be careful, though! Don't choose (A). That's the value of y, but the question wants to know the value of x. Since x=3y,x=3(5)=15, which is (C).