Explanation:
x = number of cards
the production costs (PC) per day are
PC(x) = 264 + 1.1x
the sales (S) are
S(x) = 5.1x
the profit (P) per day is sales minus costs
P(x) = S(x) - PC(x) = 5.1x - (264 + 1.1x) =
= 5.1x - 264 - 1.1x = 4x - 264
we need to find the value of x, so that P(x) = 52.
52 = 4x - 264
316 = 4x
x = 316/4 = 79
79 cards must be delivered daily to make a profit of $52.