9514 1404 393
Answer:
24
Step-by-step explanation:
Let p, d, r represent the numbers of premium, deluxe, and regular tickets sold, respectively.
p + d + r = 155 . . . . . . . number of tickets sold
8p +3d +r = 409 . . . . . revenue from tickets sold
d - p = 19 . . . . . . . . . . . relation between deluxe and premium tickets
Using the third equation, we can substitute d=19+p in the other two equations.
p + (19+p) +r = 155
8p +3(19+p) +r = 409
Subtracting the first of these equations from the second, we get ...
(11p +r +57) -(2p +r +19) = (409) -(155)
9p = 216 . . . . . . subtract 38 and simplify
p = 24 . . . . . . . . divide by 9
24 premium tickets were sold.
