20.00 + 4.00 + 00.50 + 00.08
To write expanded from take each number from left to right and turn all the numbers that are after it into zeros (if there is a decimal then turn the numbers before it into zeros as well)
2 has 4 numbers after it so it gets 4 zeros: 20.00
4 has 2 numbers after it so it gets 2 zeros: 4.00
5 is a decimal that has two numbers before it and one after, so before the decimal there are two zeros, then after the decimal comes the five, then there is one number after the 5 so one zero after the five.
8 is a decimal that has three numbers before it , so before the decimal there are two zeros, then after the decimal is a number that becomes zero then the 8
Hopefully that made sense to you and was helpful! Let me know!