Answer:
its C $12.40
Explanation:
So regular price is $7.90 a pair
and now they are on sale THREE PAIR for $17.50, Now esteban bought SIX PAIR os sock
17.50+17.50 = 35
Lastly if you put it regular price $7.90x6 pairs = 47.4
Now for the final result
47.4 - 35 = 12.40 esteban save up