5/20 - 8/20 = -3/20
+++
I was beaten to it by someone unwittingly possibly helping the questioner cheat. I had submitted:
Solve by converting the two fractions to share their lowest common denominator, then subtract the numerators.
HINT: this particular question has a negative answer!
If you're wondering why I've told you how to do it, not the answer, I suspect it's a homework question that lets you practice the technique, so you asking us to complete it for you is self-defeating for you.
2 minus 2/5 plus 1/2 minus 4 = -1.9
It is: 4/5 minus 1/2 = 3/10
-1/4
10/12 minus 2/4 is 1/3
-1/2 4/4= 1 1-2= -1 -1/2= negative one half
1/6
1/6
2/5 = 4/10 minus 1/10 is 3/10
3/6 minus 2/8 is 1/4
2 and 1/12 minus 1 and 1/3 = 3/4 or 0.75
It is: 1/2
1 1/4 minus 2/3 is 7/12