perfume is sold in 2 different sizes of bottles. the 80ml bottle is priced at £55. The 50ml bottle is usually priced at £45, but is on special offer. If you one 50ml bottle of perfume, you can get a second for half price. By calculating the price per ml, determine which offers the best value for money, the 80ml bottle, or two 50 ml bottles? You must show your working.

Sorry for the $ sign, I meant that pound sign, my computer doesn't have that sign, sorry. So just bear with me, the math is all the same.

The next one is $45+$22.5 = $67.5 for 100 ml. We can then form ratios:

55:80

67.5:100

We can then divide the first ratio by 80 on both of the sides. So we will get

0.688:1

And do the same with second but for 100

0.675:1

So since we are not counting discount on the 80 ml bottle, the best choice is the 50ml bottle with the discount one.

The 50ml bottle