2/5 - 7/8, 2/5 - 3/10
You have to find a common denominator. I'll do the first one for you. 5 and 8 both have 40 as their lowest multiple.
16/40-35/40=-19/40
Post the answer to the second one if you want it checked.
16/40-35/40=-19/40
Post the answer to the second one if you want it checked.