What is the answer to the digit 7 in 0.37 has a the value of the 7 in 0.73?

What do you mean? 7 in 0.37 is 0.07 or 7 hundredths.
7 in 0.73 is 0.7 or 7 tenths?
Is that what you meant...

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.