First, calculate the amount of fizzy water John will need. If the ratio of apple juice to water is 1:10, then you can multiply the volume of apple juice by 10 to get the volume of fizzy water needed.
500mL x 10 = 5,000mL of fizzy water
Divide 5,000mL of fizzy water by 1,500 to get 3.33...
The minimum number of soda bottles that John will need to buy is 4, because you can't buy a third of a bottle.
Hope this helped!
