Solution:

Jason has 40 balls and Glenn has 24 balls.
If Jason would give Glenn 8 balls, they would have an equal number (i.e., 32 balls each).

If Glenn would give Jason 8 balls, then Jason would have 48 balls and Glenn would have 16 balls.
Thus, Jason would have 3 times as many balls as Glenn.

Detailed Solution through Equations:

If Jason would give Glenn 8 balls, they would have an equal number.
This implies that Jason has 16 balls more than Glenn.

If Jason has j balls, then Glenn has (j − 16) balls.

If Glenn would give Jason 8 balls, then Glenn would have ( j − 24) balls and Jason would have (j + 8) balls.
Now, Jason would have 3 times as many balls as Glenn.
This may be written in the form of the following equation.

j + 8 = 3 (j − 24)

The equation may be solved as follows.

2 j = 8 + 3 × 24 = 80 ; or
j = 80 / 2 = 40.

Food for thought:

Can you solve this puzzle without writing any equations?