
Gretchen V. answered 04/29/20
Northwestern Grad Student Specializing in Math, Reading, and Writing
We have 2 variables (cost of movie and cost of video game) and we need 2 equations to find them. Let's say the cost of movies is M and the cost of video games is V. In the first month, Dan rented 5 movies (5M) and 3 video games (3V) for $37.
5M + 3V = 37 (equation 1)
The next month, he rented 2 movies and 6 games for $40.
2M + 6V = 40 (equation 2)
Let's isolate one of the variables. I choose to isolate M in equation 2:
M = (40 - 6V) / 2 = 20 - 3V
Now, substitute our new equation 2 into equation 1.
5*(20 - 3V) + 3V = 37
100 - 15V + 3V = 37
100 - 37 = 15V - 3V
63 = 12V
V = $5.25
Now, substitute the value of V into one of our earlier equations to find M.
M = 20 - 3V = 20 - 3*5.25
M = $4.25