Here are two adverts for cornflakes:
750g box
Normal price £1.98
Buy one box,
get 2nd box half price
500g box
Normal price £1.75
Buy one box,
get one free
a) Which is the cheapest way to buy 1500g of cornflakes,
A: two 750g boxes
B: three 500g boxes?
or
b) How much does it cost to buy 1500g of cornflakes,
if you use the cheapest way?