Question

Phil bought two hamburgers and a milk shake

for $10.30. Janice bought three hamburgers and

a milk shake for $14.80. What is the cost of the

two milk shakes?

A. $1.30

B. $1.45

C. $2.60

D. $4.50

Answer 1

C.

Explanation:

`\left \{ {{2x+y=10,3} \atop {3x+y=14,8}} \right.`

`\left \{ {{y=10,3-2x} \atop {y=14,8-3x}} \right.`

10,3-2x=14,8-3x

x=4,5 - one hamburger

y=1,3 - one milk shake

OR:

$14,8-$10,3=$4,5 - one hamburger

2*4,5+y=10,3

y=1,3 - one milk shake

2y=2,6