SOLUTION: Keith paid $21.43 for a collection of seven tapes.Some were on sale for $3.94 and some for $1.89.How many each type did he buy?

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Question 1153891: Keith paid $21.43 for a collection of seven tapes.Some were on sale for $3.94 and some for $1.89.How many each type did he buy?
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Is some information missing?
x, the size of the collection
h, the size for the $3.94 tapes
x-h, the size for the $1.89 tapes

3.84h%2B1.89%28x-h%29=21.43
You might be able to find whole number values for h and x which work.


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,...collection of seven tapes...
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x=7
-
3.94h%2B1.89%2A7-1.89h=21.43
%283.94-1.89%29h=21.43-1.89%2A7
h=%2821.43-1.89%2A7%29%2F%283.94-1.89%29
h=4

4 of the $3.94 tapes
3 of the $1.89 tapes

Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.

One-equation setup is THIS equation


    3.94x + 1.89*(7-x) = 21.43.


From the equation, express x and calculate


    x = %2821.43-7%2A1.89%29%2F%283.94-1.89%29 = 4.


ANSWER.  4 for $3.94 and (7-4) = 3 for $1.89.

Solved.

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Ignore post by @josgarithmetic,  since it is   W R O N G   (as usual).