Question 155407
4x=-5y+40
 x=-y+9 MULTIPLY THIS EQUATION BY -4 7 ADD.
-4X=4Y-36
4X=-5Y+40
--------------
0=-Y+4
Y=4 ANSWER. 
X=-4+9
X=5 ANSWER.
PROOF:
4*5=-5*4+40
20=-20+40
20=20