Answer:
Joe is 9 years old
Explanation:
We can start by creating two different equations, one for each fact that we know about their ages.
Say that J is Joe's age
Say that T is Tim's age
Our first equation would then be:
4J + 2T = 50
J - 2 = T
Now that we know that T is J - 2, we can plug that in to the first equation.
4J + 2(J - 2) = 50
We can simplify this equation to solve for J
4J + 2J - 4 = 50
6J = 54
J = 9
Joe is 9 years old