Markup means they sell it for that percentage more than they bought it for. First let's calculate how much they will mark it up for:

Convert 87% into a decimal(87/100):

Multiply:

This is how much they'll mark it up, now let's add it to how much they bought it for to find out the selling price:
For this case we have:
By trigonometric property we have:

Where:

Substituting:

Clearing x we have:

Thus, the equation is: 
Answer:

Yes, (3, 2) is a solution to y = 2x - 4. (: