Big Book Test 3, Section 6, Q11


Hi All- I am having trouble with the above problem. Could someone help me out?

X = 2Z
Y = Z/2 + $3
Y = X/4 + $3 (on substituting Z = X/2)

I checked for X=4 (since X/4 in the last equation); in this case Y=4
then I checked X=100 and in this case Y=28
Therefore, D