Question

How many computers must the AB Computer Company sell to break even? Let x be the number of computers.

Answer 1

You break even if you spend exactly as much as you gain. In other words, if the cost and the revenue are the same:

$C(x)=R(x) \iff 145+0.25x=1.5x$

Subtract 0.25 from both sides:

$145=1.25x$

Divide both sides by 1.25:

$x=\dfrac{145}{1.25}=116$

So, they must sell 116 computers to break even. If they sell less, they'll lose money. If they sell more, they'll start making profit.