First you have to expand the bracket then you can simplify so..
3(2+5r)+11 becomes...
6+15r+11 because 3x2=6, 3x5r=15r and you don't have to do anything to the 11 yet so now we can simplify this expression
6+15r+11 becomes 15r+17 because we can add 6 and 11 to equal 17 but we can't 15r because of the 'r' in front of it
I hope that helps you understand it
