Answer:
275mm=27.5cm
Step-by-step explanation:
We know that 1 centimeter is equal to 10 millimeters (1cm=10mm). As they are the same, dividing one by the other, results in 1:

If we multiply something by 1, it's not affected. We will multiply 275mm by 1 (or 1cm/10mm) in order to get the same quantity, but with different units:
