Answer
Less than 200 checks in a month.
Work Step by Step
Let $ x $ be the number of checks written in a month.
Better deal = smaller cost to the client.
We want x for which
(Cost of credit union) $ \lt $ (Cost of local bank)
$2+0.08x \lt 8+0.05x\qquad $ ... add $-0.05x-2$
$0.03x \lt 6\qquad $ ... multiply with $\displaystyle \frac{100}{3}$
$ x \lt 200$
If less than 200 checks are written in a month, the credit union is a better deal.
