Practice!

Sample Problem

A fast food restaurant sells either small hamburgers or large hamburgers. If one person buys 3 small hamburgers and 5 large hamburgers and spends $33.60, and another person buys 4 small hamburgers and 4 large hamburgers and spends $31.60, calculate how much each burger costs.

Small hamburger: $

Large hamburger: $

Solution

First we write a system of equations for this situation, then solve

(3x + 5y = 33.60) × 4 = 12x + 20y = 134.4

(4x + 4y = 31.60) × (-3) = -12x – 12y = -94.8

12x + 20y = 134.4

-12x – 12y = -94.8

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8y = 39.60

y = 4.95

3x + 5(4.95) = 33.60

3x = 8.85

x = 2.95

So each small hamburger costs $2.95 and each large hamburger costs $4.95.