First one
(r - c)(4) = r(4) - c(4) =
[ 4^2 + 6(4) + 10 ] - [ 4^2 - 4(4) + 5 ] =
[ 16 + 24 + 10 ] - [ 16 - 16 + 5 [ =
50 - 5 =
45
This means that the store will have a profit of $4500 after 4 months
Second one.....a little tricky to interpret !!!
(p*c)(2) = p(2) *c(2) =
[ 80 - 2(2) ] * [ 50 + 5(2) ] =
[ 76] * [ 60 ] =
$4560
The "2" represents the number of $5 ncreases above $50 = 2*5 + 50 = $60 per customer
So...the company can expect $4560 in revenue when they charge $60 per customer