The whole number multiply by the denominator and add to the numerator.
which is similar to n:1 where 
<u>Step-by-step explanation:</u>
Here we have to Express in the form n:1 give n as a decimal 21:12 . Let's find out:
Given ratio as 21:12 . Let's convert it into n:1 , where n is decimal
⇒ 
⇒ 
⇒ 
⇒ 
⇒
{ dividing denominator & numerator by 4 }
⇒ 
⇒ 
⇒
which is similar to n:1 where 
Answer:
Unit rate is often a useful means for comparing ratios and their associated rates when measured in different units. The unit rate allows us to compare varying sizes of quantities by examining the number of units of one quantity per one unit of the second quantity. This value of the ratio is the unit rate.