Question

How many pounds of candy worth 70 cents a pound must be mixed with 30 pounds of candy worth 90 cents a pound to produce a mixture which can be sold for 85 cents per pound?

A) 5 pounds
B) 10 pounds
C) 15 pounds
D) 12 pounds

Answer 1

B) 10 pounds

Step-by-step explanation:

Let x represent the amount of 70¢ candy to be added. The value of the mixture can be written as ...

... 90×30 + 70x = 85×(30+x) . . . . . where 30+x is the total weight of the mix

... 2700 +70x = 2550 +85x

... 150 = 15x . . . . . . add -70x-2550

... 10 = x . . . . . . . . . divide by the coefficient of x

10 pounds of candy at 70¢/lb must be added.