Chapter 9.3, Problem 13P

To determine

To find: The cost of a carton of milk.

Answer to Problem 13P

The cost of a carton of milk is $\$1.4$ .

Explanation of Solution

Given:

The total money is $\$5$ .

Calculation:

Let $x$ be the cost of hamburgers and $y$ be the cost of one carton of milk.

From the given information,

  $\begin{array}{c}2x+y=5\\ y=5-2x\end{array}$ …… (1)

And,

  $x+2y=4.60$ …… (2)

Substitute $y=5-2x$ in the equation (2).

  $\begin{array}{c}x+2\left(5-2x\right)=4.60\\ x+10-4x=4.60\\ 3x=5.4\\ x=1.8\end{array}$

Substitute $x=1.8$ in the equation (1).

  $\begin{array}{c}y=5-2\left(1.8\right)\\ =5-3.6\\ =1.4\end{array}$

Therefore, the cost of a carton of milk is $\$1.4$ .