Algebra II?

Question

Jenny Johnston bought some apples for 79 cents per pound and twice as many pounds of bananas for 39 cents per pound. If her total bill was $7.85, how much pounds of bananas did she buy?

Answer 1

x=pounds of apples
y=pounds of bananas

from question:

.79x+.39y=7.85 (from cost)

y=2x (from "twice as many pounds of bananas")

solving 2 variables with 2 equations:

.79x+.39(2x)=7.85 (substitution)

1.57x=7.85 (simplification of LHS)

x=5 (solving for x)

plugging back into y=2x

y=10

so since x=pounds of apples, and y=pounds of bananas

answers are:

5 pounds of apples
10 pounds of bananas.

Answer 2

10 pounds of bananas

Let x=amount of pounds of apples
Let 2x=amount of pounds of bananas

0.79x+2x(0.39)=7.85
0.79x+0.78x=7.85
1.57x=7.85
x=5

2(5)=10