6r+5 inches:
18r^2 - 27r - 35 = (3r-7) ( ) some unknown number.
You can use simple factoring to find the unknown factor by finding the other factor in the constant term and the squared term:
-7 times _ is -35; _ is positive 5
3r times __ is 18r^2; _ is 6r
That means the unknown factor, or the other side, is 6r+5 inches.
Hope that helps.
