Question 818911
<pre>
Clear of fractions first:

x/5 - y/10 = 4
x/2 + y/4 = 5 

Multiply the first one through by LCD = 10
Multiply the second one through by LCD = 4

2x - y = 40
2x + y = 20
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4x     = 60
     x = 15

   2x + y = 20
2(15) + y = 20
   30 + y = 20
        y = -10

(x,y) = (15,-10)

Edwin</pre>