The average of Amy's, Ben's, and Chris's ages is 9. Four years ago, Chris was the same age as Amy is now. In 3 years, Ben's age will be 2/3 of Amy's age at that time. How many years old is Chris now?
+36916 (a + b + c )/3 = 9
c-4 = a c = a+4
b+3 = 2/3 ( a +3) b = 2/3( a+3) - 3 Sub the red in to the top equation
(a + 2/3(a+3)-3 + a+4 )/3 = 9
2 2/3 a +3 = 27
8/3 a = 24
a = 9 then c=a+4 = 13 y/o and b=5
