Gabriel V. answered 08/09/19
Master Mathematics and Science Teacher, ACT/SAT Test Prep Tutor
HI Cori,
You can begin by writing two equations and two unknowns. Next, Identify your variables.
p = number of pizza slices, h = number of hamburgers
The first equation will show how much the pizza and burger cost
.75 x p + 1.35 x h = 292.50
The second equation will show a relationship between the number of pizza slices and hamburgers
p - h = 40
multiply the first equation by 100 to get rid of the decimals
75 x p + 135 x h = 29,250
rewrite the second equation solving for p.
p = h + 40
Substitute the value for p in the second equation into the first.
75 x (h+40) + 135 x h = 29,250
Solve the new equation for h
75h + 75 x 40 + 135h = 29,250
75h + 3000 + 135h = 29,250
210h + 3000 = 29,250
210h = 26,250
h=125
Since p = h + 40
p = 125 + 40, p = 165
So you have 125 hamburgers and 165 pizza slices
You can check your answer by multiplying 125 by 1.35 (cost per burger) and 165 by .85 (cost per slice) and
168.75 + 123.75 = 292.50 your original total.
I hope this helps and good luck!