State 7m to 250cm as a ratio in its lowest terms

First you have to convert the numbers to the same units. Either m to cm or cm to m.

To go from meters to centimeters you multiply the number by 100.

7*100=700cm

Now you have 700cm/250cm. This needs simplified

I divided each number by 50 to get 14 and 5

14cm/5cm or 14cm:5cm