Question

for a special concert by a popular band, the concert hall owner decided to charge $20 per ticket for the first "r" rows and $15 for the remaining rows. remember, there are a total of 40 rows with 20 seats in each row and the expense to operate this concert is $275.

Answer 1

r = 16 according to the problem, so the total amount of income will be:
$20*16 + $15*(40 - 16)
= $320 + $15*(24)
= $320 + $360
= $680
that is the income, but the expenses are $275 so the total revenue is the subtraction of those two
total revenue = $680 - $275
= $405