The formula in computing the break-even point is:
Break-even = fixed cost / contribution margin
The fixed cost is already given which is $1700 per month. To compute for the contribution margin, you have to deduct the average cost per month ($75) to the selling price of each bicycle ($95). The contribution margin is $20 ($95 - $75).
Substituting the amounts to the formula:
Break-even = $1,700/$20
= 85
Therefore, the store must sell 85 bicycles each month to break even.