the ratio 2.5 metres to 70 centimeters can be written in the form 1:nfine the value of n

First analyze your data.
2.5 meters to 70 centimeters.
And you have to convert 1 meters to n centimeters.
So make a proportion.

2.5/ 70 = 1/n

The 2.5 and the one are both on top because it is the same unit, meters.
Then multiply and divide like so...

70*1=70 now 70/2.5=28

So 28=n.