Hi,
A)

B)
Only if n=4*k or n=4*k+1 , k beeing an integer.
1 treat is 19 cents so you multiply 250 by 0.19 and you get 47.50 then take the $19.95 the amount for a package of treats and minus it from 47.50 and you save $27.55
No. It's rather simple, down to addition. Ask yourself, what does 6 + 8 equal? 6 + 8 = 14. Now is this an odd number? No, 14 is an even number.
I hope this helps! If not I'm sorry.