Replying to your PM, I guess you are also making the same silly and also much disastrous mistake.
Expand carefully and notice the difference between the equations.
Moreover, If you are applying the same method of mine then after getting the final values, put them in the respective equations. The equation won't satisfy.
Yes Marcab i got solution that VIPS and others stated...
sorry for the offense VIPS
but i'm eager enough to know about my mistake... (or even the way marcab did)
I donno where i did mistake in substitution method
But i'm getting solution in solving two equation
GMAT - Practice, Patience, Persistence
Kudos if u like