This problem is about proportions.
We need to remember that a proportion is an equality between two ratios.
This problem is giving us two ratios.
Ratio 1: $31.25 for 5 square yards.
Ratio 2: $71.50 for 11 square yards.
Now, we form the equality

Then, we divide each fraction

As you can observe, this result is false, which means the initial ratios are not in the same proportion.
Therefore, the relationship is not proportional.