SOLUTION: A nut shop sells almonds for $7.75 per pound and peanuts for $3.25 per pound. in order to sell an overstock of peanuts, the shop owner decides to mix the peanuts and almonds. How m

Algebra ->  Customizable Word Problem Solvers  -> Mixtures -> SOLUTION: A nut shop sells almonds for $7.75 per pound and peanuts for $3.25 per pound. in order to sell an overstock of peanuts, the shop owner decides to mix the peanuts and almonds. How m      Log On

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Question 692994: A nut shop sells almonds for $7.75 per pound and peanuts for $3.25 per pound. in order to sell an overstock of peanuts, the shop owner decides to mix the peanuts and almonds. How many pounds of each kind of nut are in a 4 pound mixture that costs $19?
>>>I do not know how to set up the equation my professor doesn't explain problems well. Also, I want to know what are each of the steps involved in this equation I tried finding a similar problem in the book but was unsuccessful.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = pounds of almonds needed
Let +b+ = pounds of peanuts needed
given:
(1) +a+%2B+b+=+4+
(2) ++7.75a+%2B+3.25b++=+19+
Note that this is just
( cost of almonds used ) + ( cost of peanuts used ) = ( cost of mixture )
---------------------------
Most of the other problems are a little different.
Most give the cost/pound of the final mixture
instead of the total cost of the final mixture.
It doesn't really matter- just an observation.
--------------------------------------
(2) +775a+%2B+325b+=+1900+
Multiply both sides of (1) by +325+ and
subtract (1) from (2)
(2) +775a+%2B+325b+=+1900+
(1) +-325a+-+325b+=+-1300+
+450a+=+600+
+a+=+1.333+
and, since
(1) +a+%2B+b+=+4+
(1) +1.333+%2B+b+=+4+
(1) +b+=+4+-+1.333+
(1) +b+=+2.667+
1.333 pounds of almonds are needed
2.667 pounds of peanuts are needed
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check:
(2) ++7.75a+%2B+3.25b++=+19+
(2) ++7.75%2A1.333+%2B+3.25%2A2.667++=+19+
(2) ++10.3307+%2B+8.6678+=+19+
(2) +18.998+=+19+
I think the error is due to rounding off