Answer:
7.770
Explanation:
Amelie originally wrote her number with only two decimal places, 7.77. This only includes the tenths and hundredths places. In order to have one more decimal place, she needs to add a zero after the last digit. Therefore, her number should be written as "7.770" because this consists of a thousandths place. With this number, she can then compare her number to Matthew's 7.707.
We can conclude that Matthew's number is less than Amelie's number.