Mixture word problems

Question

Paul mixes nuts worth $1.45 per pound with oats worth $1.70 per pound to get 20 pounds of trail mix worth $1.55 per pound. How many pounds of nuts and how many pounds of oats did he use?

Answer 1

1.7x + 1.45(20-x) = 1.55(20)

.25x = .1(20)=2

x=2/.25

x =8 lbs $1.70

mixed with 12 lbs $145

to get 20 lbs $1.55

another method is:

1.7 - 1.55 = .15

. 1.55 - 1.45 = .10

.15/.10 = 3/2 = 1.5

use 1.5 times as much $1.45 as $1.70

x/(20-x) = 1.5

30 -1.5x = x

2.5x =30

x = 30/2.5 = 300/25= 12 lbs $1.45

8 lbs $1.70