Question

A pair of pants costs twice as much as a shirt. The total cost of 1 pair of pants and 1 shirt is $18. If s represents the cost of 1 shirt, which equation could you use to find the cost of 1 shirt?

Answer 1

The total cost of 1 pair of pants and 1 shirt is $18 . If s represents the cost of 1 shirt, which equation could you use to find .

Answer 2

For this case we propose a system of equations:

p: Variable representing the cost of a pair of pants

s: Variable representing the cost of a shirt

A pair of pants costs twice as much as a shirt, means:

`p = 2s`

The total cost of 1 pair of pants and 1 shirt is $ 18:

`p + s = 18`

We substitute the first equation in the second:

`2s + s = 18\\3s = 18\\s = \frac {18} {3}\\s = 6`

Answer:

The following equation can be used:

`2s + s = 18`