Answer:
13 y/o
Explanation:
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
10
Check by going backwards
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