Seven inches are equivalent to 17.78 cm. 

Therefore,



Solve that for cm.

Divide both sides by 17.78



}

Write  as 
and reverse the equality:



Let N = the number of centimeters
we wish to convert.

Then we multiply both sides by N:



That's the formula.

Therefore to find the length in inches of a 96.2 cm bar,
we substitute 96.2 for N:





Edwin