Question

Your class decides to publish a calendar to raise money. The initial cost, regardless of the number of calendars printed, is $900. After the initial cost, each calendar costs $1.50 to produce. What is the minimum number of calendars your class must sell at $6 per calendar to make a profit of at least $1200?

Answer 1

Revenue - Cost = 1200
Let N be the number produced (and sold)
The revenue is 6N.
The cost is 900 + 1.5 N.

1200 = 6 N - (900 + 1.5N)
= 4.5 N -900
4.5 N = 2100
N = 467
N has to be an integer, so you round to the next higher integer.
N=466 would result in a loss.