Answer:
a) y is four times bigger
b) y is 9 times bigger
c) y is four times smaller
d) y is 16 times smaller
Explanation:
Let's assume that our initial comparisson value is y0.

a) if x is doubled:
:
y is four times bigger
b) if x is tripled:
:
y is 9 times bigger
c) if x is halved:
:
y is 4 times smaller
d) if x is quartered:
:
y is 16 times smaller