Question 59848
X-Y=7 OR X=7+Y
4X-5Y=25 SO
4(7+Y)-5Y=25
28+4Y-5Y=25
-Y=-3
Y=3 THEN 
X-3=7
X=7+3
X=10
PROOF
4*10-5*-3=25
40-15=25
25=25