Technically the answer would be 8.51 meters and 73 cm, however, I don't think that is the answer they are asking for. I think you need to convert either meters to centimeters or centimeters to meters.
Meters to Centimeters: In order to convert meters to centimeters, you will move the decimal point back by two spaces. So what was 8.51m (move decimal two spaces) is now 851cm. "Part Two" Now add 851cm + 73cm = 924cm
OR...
Centimeters to Meters: In order to convert centimeters to meters, you will move the decimal point forward by two spaces. So what was 73cm (move decimal two spaces forward) is now 0.73m. "Part Two" Now add 8.51m + 0.73m = 9.24m
