Question 1154244
This example looks like another similar or identical one solved about a week ago.

<pre>
COFFEE        PRICE       QUANTITY        COST

  A           14.99        a             14.99a

  B           13.99        b             13.99b

  C           10.39       2a            2*10.39a

TOTALS                    51 
Avg.          12.61             
</pre>

Form two equations in the unknowns a and b:
{{{system(3a+b=51,14.99a+2*10.39a+13.99b=12.61*51)}}}
Simplify and solve the system.


{{{system(3a+b=51,35.77a+13.99b=643.11)}}} simplified system.


If choosing substitution of b, then:
{{{35.77a+13.99(51-3a)=643.11}}}
{{{35.77a+713.49-41.97a=643.11}}}
{{{(35.77-41.97)a=643.11-713.49}}}
{{{-6.2a=-70.38}}}
{{{a=70.38/6.2}}}
{{{highlight(a=11.35)}}}

and you can solve for b and for 2a, and should check that the solutions work.
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