+9519 If Lewis bought 4 single cartons, then it would cost £1.8.
But if he bought a pack of 4 cartons, then it costs £1.56, which is cheaper.
If you were Lewis, you would want to buy as many packs of 4 cartons as possible.
But you can't group 38 cartons into packs of 4. That means some of the cartons has to be bought in single cartons. We will determine how many single cartons do we need buy.
Now, Lewis needs 38 cartons. But because 4 * 9 = 36 and you can't group the remaining 2 cartons into a pack of 4, the remaining 2 must be bought in cartons.
So in total, we need to buy 9 packs of 4 cartons, and 2 single cartons to group to 38.
At the same time, for easier calculation, we need to change 45p into £, which is 0.45£.
The strategy I mentioned above would cost Lewis \(£1.56\times 9 + 2\times £0.45 = \boxed{£14.94}\)
