Having 1 meter is equivalent to having 100 centimeters, then 4 meters equals 4×100 centimeters, that is 400 cm.
Since she used 235 centimeters, she left 400 - 235 centimeters, that is 165 cm, we can separate these 165 centimeters into 100 centimeters + 65 centimeters, as mentioned, 1 meter is equivalent to 100 cm, then we get:
100 cm + 65 cm
1 m + 65 cm
Then, she left 1m 65 cm of wood