Help im confused

Question

Kenneth is 8 years older than Andrew. Billy is 3 times as old as Andrew. Cameron is 5 years younger than Andrew. The combined age of the four boys is 63. How old is Andrew?  

Answer 1

k = a+8, b= 3a, c=a-5

k+a+b+c = 63

a+8 +a +3a +a-5 = 63

6a = 60

Andrew = 10 years old