Answer:
B. 294 divided by 21 = 14. she paid 14 for each t shirt
If the remaining 4 letters can be anything, you have 2*26^4 = 913,952 possible 5-letter ham radio call signs.
It might be y=4x but then that would mean something else on the table is wrong
-2y+6y. 44-16
4y. 28
28 divided by 4 = 7