That's a 30-60-90 triangle, so the hypotenuse will always be 2x, the shorter leg will be x and the longer leg will be x√3. In this case, we are given the longer leg and we can deduce that x = 9. So, a = x = 9 and c = 2x = 18. Your answer is A, a = 9 yd, c = 18 yd.
3 3/4 + 1 1/4 + 2 2/4
3/4 + 1/4 + 2/4 = 1 1/2
3 + 1 + 2 + 1 1/2 = 7 1/2 cups total