ellen mixes candy 2.48 per pound with candy worth 3.50 per pund to form 17 lbs. of a mixture worth 2.69 per lb. how many lbs expensive candy should she use

Question

please help!!!!! its 2.96 not 2.69 which changes answer.

Answer 1

michelle, not sure if you still need this, but...

 

use x for the lbs of $2.48 candy, and y for the lbs. of $3.50 candy

 

x + y =17 lbs

 

and

 

2.48x + 3.50y=17 x 2.96 (which equals total cost of $50.32)

 

note that if x + y = 17, then x by itself = 17 - y.

 

So re-do the bigger equation, subbing in "17-y" every time you see x. Don't forget: when you see 2.48 x (17-y) you need to use the distributive property, so you get

 

42.16 - 2.48y + 3.50y = 50.32

 

combine your y terms by adding them together to give you 1.02y. (that's because the 2.48 is negative--see the minus sign?)

 

so then you have 1.02 y + 42.16 = 50.32.

 

subtract 42.16 from both sides and you get

 

1.02 y= 8.16.  Divide each side by 1.02 and you get:

 

y = 8 (as in 8 lbs of that candy, which means you have 9 lbs of the other!)

 

You can can check your answer by figuring out 8 x 3.50, + 9 x 2.48.

 

If the answer to that is 50.32, you're GOLDEN! (Pssst... that is the answer :-)  )

 

hope this helps!

 

Matt

PS: don't forget to answer the question that was asked: "She will need 8 lbs of the more expensive candy." Your teacher will love ya!