A local bank charges 19 per month plus 3 cents per check. The credit union charges7 per month plus

A local bank charges 19 per month plus 3 cents per check. The credit union charges7 per month plus 7 cents per check. How many checks should be written each month to make the credit union a better deal?

Set up the cost function B(c) for the local bank where c is the number of checks:
B(c) = 0.03c + 19

Set up the cost function B(c) for the credit union where c is the number of checks:
B(c) = 0.07c + 7

We want to find out when:
0.07c + 7 < 0.03c + 19

Typing this inequality into our search engine, we get:
c < 300