Question

Lisa went to the store and bought 100 pounds of fruit for $100.00. The peaches were $10.00 a pound, the melons were $3.50 per pound, and the apples were $.50 per pound. How many pounds of each did she buy

Answer 1

amount of peaches --- x lbs
amount of melons ---- y lbs
amount of apples ----- 100 - x - y lbs
(assume both x and y are whole numbers)

10x + 3.5y + .5(100-x-y) = 100
double every term
20x + 7y + 100 - x - y = 200
19x + 6y = 100
x = (100 - 6y)/19 , clearly 0 < y < 6
by trials, y = 4, then x = 4

So he bought 4 lbs of peaches,
4 lbs of melons, and
92 lbs of apples.

check:
10(4) + 3.5(4) + .5(92)
= 40 + 14 + 46
= 100