Walt was 1.5 meters tall. There are 100 centimeters in 1 meter. So when you convert the 10 centimeters to meters, you get 0.1 meter. You can then subtract 1.6 - 0.1 to get 1.5 meters.
He is 1.5 1 meter is 100 centimeters so therefore 1.6 meters would be 160 centimeters if he grew 10 centimeters a year and is currently 1.6 or 160 centimeters subtract 10 centimeters and its 1.5 meters or 150 centimeters.
