Answer:
22 3/4 inches.
Explanation:
First what I like to do is find least common denominator.
Since 2 of the ribbons are measured in /4's, and the other ribbon is measured by half ( /2). 4 will be your new denominator making the 18 1/2 in. long ribbon 18 2/4 inches.
Now, the Blue ribbon is 3/4 greater than the Red ribbon, making it the 18 2/4 inch ribbon.
The Yellow ribbon is 4 3/4 inches longer than the Blue ribbon which means add 4 3/4's to 18 2/4, and you get = 22 3/4 in. for the yellow ribbon.
Hopes this Help!