Answer: Good Y = 14
Explanation:
utility function
U(x,y) = Utility
Good X = 10
Good Y = 12
U(x,y)= 10x + 5y
U(x,y) =10(10) + 5(12)
U(x,y) = 160
when good a drops by 1 Good X will 9
160 = 10(90) + 5y
5y + 10(90) = 160
5y = 160 - 90
5y = 70
y = 14
When Good X is lowered by 1 to maintain the level of 160 utility Good Y must be 14