When x increases from a to a + 2, y increases by a factor of 1/4

y=7 * (0.5) ^x

Step-by-step explanation:

We are given that when x increases from 'a' to 'a+2' then y must increase by a factor of 1/4=0.25.

i. e. when x=a and x'=a+2.

then y/y=0.25 where y' is the function after putting x' to the old function.