6 candy boxes
Step-by-step explanation :
Since they both bought their own popcorn that means they both spent $8 on popcorn making that a total of $16. Therefore we now only need to find one variable which is the number of candy boxes that they bought in order to reach the $25 total that they spent. This variable can be represented as x in the following algebraic equation.
(2*8) + 1.50x = 25
16 + 1.50x = 25 ... subtract 16 from both sides
1.50x = 9 ... divide both sides by 1.50
x = 6
Finally, we can see that Billy and Tommy bought a total of 6 candy boxes.