Question 771536
          3x+4.25y=87.5
               x+y=25
<pre>
Solve the second equation for x
 
                 x = 25 - y

Substitute (25 - y) for x in the first equation

 3(25 - y) + 4.25y = 87.5

   75 - 3y + 4.25y = 87.5

        75 + 1.25y = 87.5
     
             1.25y = 12.5

                 y = {{{12.5/1.25}}}

                 y = 10

 

Substitute 10 for y in

                 x = 25 - y

                 x = 25 - 10

                 x = 15

Edwin</pre>