x+ y =20 (a)
32x+54y= 816 (b)
Multiply (a) by 32 and subtract (a) to (b). Then solve for y:
32x+54y= 816
-
32x+32y=640
___________
22y= 176
y= 176 /22
y= 8
Replace y on (a) and solve for x
x+8=20
x=20-8
x=12
Solution:
(x,y) = (12,8) option c
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