You can divide each amount to see how much one yard is and then go on from there. For the first one do 20 (the cost) divided by 5 (how many yards you get and you get 4. That means it is $4 per yard and then does the rest the same way.
30/10 = $3 per yard
55/20 = 2.75 per yard
90/35 = 2.67 (rounded) per yard.
So the best deal would be D. because it costs less per yard. I hope this helps!
