A piece of timber is x cm long. 7 cm is cut off. How much is left?

x-7>0

Straight answer: x-7

Step-by-step explanation:

Assuming that the timber is X cm long and 7cm was cut off, there remaining amount is x - 7cm. In order for 7cm to be cut off, the timber must have been > 7cm long = > x > 7 = > x - 7 > 0