Add or subtract. be sure to reduce your answer 5\6-9/20

Greetings! 

"Add or subtract. Be sure to reduce your 5\6-9/20"...

To add or subtract rationals, you must find a common denominator of both fractions.
This can be done by multiplying the denominators by each other:
6*20=120

We must do the same operation to the numerators.
5*20=100
9*6=54

Now we can the subtract the rationals:
100/120-54/120
=100-54/120
=46/120
=23/60

Hope this helps.
-Benjamin