To answer this question, Justin has bought 3/2 yards of the ribbon.
There are two ways you could answer this question. You could add it or subtract it. First, I will teach you the way of adding to get your answer. So, from this sentence, Justin has bought 6 ribbon and each was 1/4 yards long. You could add it by doing 1/4+1/4+1/4+1/4+1/4+1/4. This would give you 6/4, which would be 3/2 yards(simplified). (This could also be 1.5 yards..)
The second way was multiplying. It would look like this: 1/4 times 6. (Now, 6, could be represent as 6/1) Now you do 1 time 6 for your numerator and 1 times 4, which would be your denominator. This would also give you 6/4 or 3/2 (simplified) Hope this works!! :)