Data:
Initial: $25
Muffin cost: 4.6% of 25$
To calculate the 4.6% of 25 you multiply 25 by 4.6 and then divide it by 100:
Muffin cost is $1.15
The remaining money is: $23.85
spent 6% of the remaining money on a bottle of water: Multiply the remaining money by 6 and then divide it by 100 to get the cost of the bottle of water:
Then, he have left approximately $22.42