The distributable property is then something in front of parentheses is applied to both of the units in the addition problem.
That can be rewritten as (3/4x s) + (3/4 x 8)
To solve those, I tend to devide 8 by 4 and multiply it by 3 (because of the fraction) and you don’t know S so it is just 3/4 S. Then put 3/4S and (3/4 x 8) together.
Hope that helps