Michelle went shopping for some clothes and found a pair of slacks that cost

twice as much as a shirt that she liked. If the total, before tax, for the pair of

slacks and the shirt was $22.50, how much was the shirt, before tax?

The sirt cost $7.5 before tax.

Step-by-step explanation:

Since the pair of slacks cost twice as much as the shirt, we have:

slacks = 2*shirt

And the total purchase was $22.5, so we have:

slacks + shirt = 22.5

We can create a system of equations such as:

slacks = 2*shirt

slacks + shirt = 22.5

If we apply the first formula on the second we can solve for the value of the shirt, we have:

2*shirt + shirt = 22.5

3*shirt = 22.5

shirt = 22.5/3 = 7.5

So the slacks cost:

slacks = 2*7.5 = 15