Answer: 5(3n+4r)
Step-by-step explanation:You need to find the gcf/factor .So the gcf of 15 and 20 is 5.So know that you know the gcf ,you divide 15n by 5 which gives you 3n and divide 20r by5 which gives you 4r.Now the last thing you do is,take the GCF which is 5 and place a Parentheses and take 3n and 4r and add them together.
So you get 5(3n+4r) as your expression that is equivalent to 15n + 20r .
Hope it helps . :)
