This equation is written with the number of of birdhouses = x
The cost of making the birdhouses is $80 plus $6.25 per birdhouse
80 + 6.25x
He will sell each bird house for $16 each
16x
The profit (16x) should be greater than (>) the cost (80 + 6.25x)
16x > 80 + 6.25x
16x - 6.25x > 80
9.75x > 80
x >8.205....
We can therefore establish that the answer will be around 9