1/4n-8=1/4 would be first because it says less than so you switch it. then you put the 8 since it's in the same subtraction problem. Then the word "is" indicates the equal sign. and the n represents "a number" since it is unknown.
2 years will be 80 cats (20 x 2 = 40 (year 1) and 40 x 2 = 80 (year 2))
3 years will be 160 (80 x 2 = 160)
5 years will be (160 x 2 = 320 (year 4) and 320 x 2 = 640 (year 5)) So 5 years will be 640
I just know the answer is 28