At the supermarket Pryslide, 500ml bottles of shower gel cost $7 each. However, since the beginning of last week there has been a special offer: ‘Buy 2 bottles, get another one for $2.'

I strongly believe that the question requires us to calculate the cost of one 500ml bottle of shower gel based on this special offer of buy 2 bottles get another for just $2.

The correct answer is $5.33

Step-by-step explanation:

From a buyer's point of view,a 500ml bottle of shower gel cost is the $7 multiplied by 2 bottles plus $2 multiplied by 1 bottle all divided by 3 bottles.

The rationale for the denominator is that the total number of bottles bought would then equal 3 bottles .

Cost per bottle =($7*2)+($2*1)/3=$16/3=$5.33

Instead of a bottle costing $7,under the special arrangement a bottle would simply cost $5.33