Stall A sold watermelons at $4 each and Stall B sold pineapples at
$2.50 each. The number of watermelons in Stall A was 3/4 as many as the
number of pineapples in Stall B. When Stall A sold 52 watermelons, Stall B
gave Stall A the same number of pineapples to sell. The ratio of the number
of pineapples in Stall B to the number of fruits in Stall A now is 7:15.
Find the total cost of the watermelons and pineapples at first.
+130071 Call the number of pineapples originally in Stall B = P
Call the number of watermelons originally in Stall A = W
And we know that (3/4)P = W
When Stall A sells 52 watermelons and gets 52 pineapples from Stall B, it still contains
W fruits = (3/4)P
And, at the end, Stall B contains P -52 pineapples
And the ratio of the number of pineapples in Stall B to number of fruits in Stall A = 7/15
So
P - 52 7
_____ = ____ cross-multiply
(3/4)P 15
15 (P -52) = 7(3/4)P
15P - 780 = (21/4)P
15P - (21/4)P = 780
(60 - 21) / 4 * P = 780
39 / 4 * P = 780
P = 780 * (4/39) = 20 * 4 = 80 pineapples in Stall B at first
(3/4) P = (3/4) * 80 = 60 watermelons in Stall A at first
Total cost of all the fruits at first = 60 ( $4) + 80 ($2.50) = $240 + $200 = $440
