Billy and ryan had a competition at the batting cage. billy hit 7 balls for every 4 balls ryan hit. billy and ryan hit a total of 99 balls. how many balls did each boy hit?

We are to find the number of hits Billy and Ryan had in this game. We are then to find 2 thing or in other words there are 2 variables that we have to solve. As a rule we need to find 2 relationships. The 2 relationships or equations are: 

B + R = 99

or 4B - 7R = 0 
where B- Billy's hit and R - Ryan's hit. 

B= 63
R=36

Plug in the value
(2.5 + 4)^2
Remember that parenthesis should go first: 2.5 + 4 = 6.5
Now square that. (6.5)^2 = 42.25
The solution is 42.25