Using substitution, which number from the set {8, 12, 16, 20}

12

12 is the solution only if the original equation was

x/4 + 2 = 5
I wish these users would learn how to type math!!!!!!!!!!

My apologies for misunderstanding the original equation.

In that case, let's find the correct solution using substitution:

x/4 + 2 = 5
x/4 = 5 - 2
x/4 = 3
x = 4 * 3
x = 12

Therefore, the correct number from the set {8, 12, 16, 20} that makes the equation x/4 + 2 = 5 true is 12.