Math Word Problem Help? (pounds/money...)

Hello. I am trying to study for a big test coming up in my school. They gave us this big packet to study from, and there is this one word problem I just can't remember how to do! I feel like it has something to do with setting up a chart... but I'm really not sure! Anyway, I'd really love it if you can explain the steps on how to do this problem. Thank you so much.

PROBLEM:
Jena mixed 8 pounds of raisins that cost $2.50 per pound with peanuts that cost $3.75 per pound to make a mixture that cost $3.35 per pound. How many pounds of peanuts did Jena use?

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Okay! Thanks!

let x lbs of peanuts be used, then

2.5*8 + 3.75x = 3.35(8+x)

0.4x = 8(3.35-2.5) = 6.8

x = 17 lbs of peanuts
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.2266666666666667 or aprox. .23 lbs was the pounds of peanuts Jena used. The way i solved was like this, 8lbs x raisins($2.50) = $20.00 dollars being to total amount of raisins. then you multiply the amount of the mixture by 8lbs 3.35 x 8lbs= to equal 26.8. then you subtract the mixture with the raisins and you get 6.8, 20 - 26.8= 6.8. then you divide 6.8 by 8 remember that both answers we got were from, we multiplied by 8lbs and we need need to find 1lbs. 6.8/8 gives us .85 and now you divide that amount by the price 3.75 and get .2266666666666667 or aprox. .23lbs

ok now that i re-read it i found another way to do it. since we know that 8 pounds were used to do it, we can establish that 2.50 is spent on raisins of the 3.35 per lbs mixture. we then subtract 2.50 raisins to leaves us with the peanuts which is .85 cents of peanuts, all we gotta do is multiply .85 by the price of pounds to get how much .85 cents of penuts are .85 x 3.75 = .2266666666666667 or aprox. .23 lbs.