Question

The cost of 5 boxes of envelopes and 5 packages of notebook paper is $25.38. How much would one box of envelopes cost?

Answer 1

1. Let the cost of 1 box of envelopes be

$$x$$

. One package of notebook paper costs

$$y$$

. We see that

$$5x+5y=25.38,$$ $$x+y=\frac{25.38}{5}=5.076.$$

2. One box of envelops hence costs

$$x=5.076-y.$$

3. If you know the cost of one package of paper, simply substitute it for

$$y$$

. If you know the total cost of other quantity of boxes and packages, write an equation similar to the first one in pt.1, express

$$y$$

in terms of

$$x$$

and substitute it for

$$y$$

in the equation in part 2.