Question

An energy bar company manufactures peanut butter and chocolate bars.
Peanut butter bars cost 25¢ per lb.
The chocolate bars cost 30¢ per lb.
The company sold 260 lbs of bars for $71.
How many of the bars sold were peanut butter?

Answer 1

Peanut Butter = P
p + c = 260
c = 260 - p .................... Eq. 1

0.25p + 0.3c = 71
25p + 30c = 7100 .......... Eq. 2


Sub 260 - p from Eq. 1 for c in Eq. 2:

25p + 30(260 - p) = 7100
25p + 7800 - 30p = 7100
- 5p = 7100 - 7800
- 5p = - 700
p = - 700 / - 5
p = 140

Answer 2

Let peanut butter bars sold be x lb
cost of it 25¢ per lb. = 25x

Then chocolate bars sold = (260 – x)
cost 30¢ per lb = 30(260 – x)

total cost = 25x + 30(260 – x) = 7100
25x + 7800 – 30x = 71
5x = 700
x = 140 -------- peanut butter bars
260 – 140 = 120 chocolate bars