Answer:
3 * 20s
Explanation:
In order to find out how much Mr. Hartman will spend in total we first need to multiply the price of the keyboard and mouse by the number of computers in a single computer station. Once we have these products we add them together. Finally, we multiply this new value by 3 since there are a total of 3 computer stations. If we turn this into an expression it would be the following...
3 * (13.50s + 6.50s)
We can even simplify this by first adding the cost of the keyboard and mouse and then multiplying by s
3 * 20s