Amount of money spent per day = $1800
Cost of overhead expenses per day for labor and materials = $9
Selling price of each camera = $18
a. Let us assume the number of cameras manufactured per day = x dollars
Then
Cost of cameras sold in 1 day = 18x
So
18x = 1800 + 9x
18x - 9x = 1800
9x = 1800
x = 200
From the above deduction, we can conclude that the number cameras sold per day is 200
b. Daily selling amount of 250 cameras = 250 * 18
= 4500 dollars
Daily manufacturing price of 250 cameras = 1800 + (9 * 250)
= 4050 dollars
Then
Daily profit = 4500 - 4050
= 450 dollars