If $A:B:C = 2:1:4$, what is the value of $(3A + 2B) \div (4C - A)$? Express your answer as a common fraction.
In the given ratio, A = 2B and C = 4B
So
[ 3 (2B) + 2B ] / [ 4(4B) - 2B ] =
[ 8B ] / [ 14 B ] =
8 / 14 =
4 / 7
