The difference between 19.79 and 9.08 is found by subtracting the two numbers.
Hence,
[tex]19.79-9.08=10.71.[/tex]
The estimate of the difference is done in the following manner.
19.79 is close to 20 and 9.08 is close to 9; therefore, the easier subtraction we have to do is 20 - 9 = 11.
