Final answer:
To compare the heights of Tommy and Harry, we need to convert millimeters to centimeters and compare the measurements. Both Tommy and Harry are 100 cm tall.
Step-by-step explanation:
To determine who is taller, we need to compare the measurements given in centimeters and millimeters. Tommy is 100 cm tall, while Harry is 1000 mm tall. In order to compare these measurements, we need to convert the millimeters to centimeters. There are 10 millimeters in 1 centimeter, so 1000 mm is equal to 100 cm. Comparing the two measurements, we find that Tommy and Harry are the same height, as both are 100 cm tall.