Data Sufficiency

Hey guys, I need help with following questions from OG 11

1. If r and s are positive numbers, r is what percentage of s? <Q8,OG11>
a. r/s = ¾
b. r+s = 75/100

2. If m>0 and n>0 , is (m+x)/(n+x) > m/n <Q143,OG11>
a. M<n
b. X>0

3. Is 1/p > r/(r^2+1) ? <Q145,OG11>
a. P=r
b. R>0


4. If n is a positive integer, is n^3-n divisible by 4?<Q147,OG11>
a. N=2k+1, where k is an integer
b. N^2 + n is divisible by 6