Okay so this is a matter of how many 0.55's go into 3.00
The best way to do this is:
Convert 3.00 to pence
3.00 = 300p
Then keep adding 55p to itself to work out how much 1 yoghurt is, 2 then 3 etc.
1 yoghurt = 55p
2 yoghurts = 110p
3 yoghurts = 165p
4 yoghurts = 220p
5 yoghurts = 275p
6 yoghurts = 330p
Okay, now 330p is 3.30 which is more than 3.00, which means that there isn't enough money for 6, but there is for 5.
EXTENSION:
To work out how much would be left over:
300 - 275 = 25p
