What is 7/9 - 5/18 lowest common denominator

Sandy is ordering bread rolls for her party,she wants 3/5 of the rolls to be whole wheat. what other factions can represent part of the rolls that will be whole wheat? shade the models to show your work.

I’m still confused on how to work the percentages

Find the condition that the zeros of the polynomial f(x) = x^3+3px^2+3px+r may be in a.p.