26*25*24*23*22=7893600
or you can use
26!/(26-5)!=7893600
2y+14=28
-14=-14
—————-
2y=14
14/2=y
Y=7
1. we know she needs 3 packs of biscuits
2. Shop A you only need to pay for 2 packs
3. Shop B you only need to pay for 2 packs
4. Shop C you need to pay for all three
5. so we know C is out of the option.

so shop A and B will cost the least
3 4/5 because when you make the denominators equal by multiplying 1/4 by 5 on both sides and 4/5 by 4 and both sides you will get 5/20 and 16/20