Algebra 1
posted by Ashley .
How do you find a common denominator when subtracting whole numbers and fractions?

Find the common denominator for the fractions.
Example:
2 3/4  1 2/5
The common denominator is 20.
2 3/4 = 11/4 = 55/20
1 2/5 = 7/5 = 28/20 
Please explain how i would do this.
8 1/9  1 6/7 =? 
Thank you sooo much for your help now it all makes sence!!!! ;))