Question 155406
If you started with:
  x +   y = 48
12x + 14y = 628
.
Start by reordering:
12x + 14y = 628
  x +   y = 48
.
Now, multiply both sides of the second equation by -12:
  12x + 14y  = 628
-12(x +   y) = -12(48)
.
  12x +   14y  =  628
 -12x + (-12y) = -576
.
Now, we're ready to combine equation 1 with equation 2:
  12x +   14y  =  628
 -12x + (-12y) = -576
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           2y  = 52
            y  = 26 (solution for y)
.
Use the above definition of y and plug it back into:
  x +   y = 48
to solve for 'x'.
.
  x +   y = 48
  x +  26 = 48
  x = 48-26
  x = 22 (solution for x)