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:
[tex]p = 2s[/tex]
The total cost of 1 pair of pants and 1 shirt is $ 18:
[tex]p + s = 18[/tex]
We substitute the first equation in the second:
[tex]2s + s = 18\\3s = 18\\s = \frac {18} {3}\\s = 6[/tex]
Answer:
The following equation can be used:
[tex]2s + s = 18[/tex]
