Ok, so 3 and 10, remember that, then remember 1 and 2. Subtract them both, and that will be your average speed.
In order to solve this we need to make on part of both statements equal.
Since 12 is divisible by 6 lets do that.
Multiply everything in the second package by 2.
It then becomes 6 pairs for $12.
So now have have 6 or 8 pairs for $12.
You are getting a different amount for the same price therefore they are not proportional.
71 is the answer your welcome