<u>Answer:</u>
He will order 72 pairs of high tops
<u>Explanation:</u>
Given the store owner sells two pairs of running shoes for each pair of high tops
For every pair of high tops, he sells 2 pairs of running shoes
1 high top = 2 running shoes
He has planned to order 144 pairs of shoes
Therefore, 144 pair of running shoes = 144/2 = 72 pairs of high tops
Therefore, he will order 72 pairs of high tops
First you have to set up your equation. 5x+80 and x+15.
Multiply the equation:

The solution set is the same, because multiplying both sides of an equation by a non-zero number doesn't change the solution set. In fact, if you rewrite the equation as

Multiplying this by 3 (or whatever number, for all it matters) gives

Now, a product is zero if and only if at least one of the factor is zero. So, either
or 
Since the first is clearly impossible, the second one must be true, which is the original equation.