A store manager has determined that the monthly profit y realized from selling a particular brand of

Question:

A store manager has determined that the monthly profit y realized from selling a particular brand of car battery is given by
y = l0x - 155
where x denotes the number of these batteries sold in a month.
(a) If 41 batteries were sold in a month, what was the profit?
(b) At least how many batteries must be sold in a month in order to make a profit?