You first need to get the same denominator so them, so you multiply the denominator, 2, by 4 to get the same denominator of 8.
Then you multiply the numerator, 1, by 4 as well to get a numerator of 4. Then you have 4 3/8 - 2 4/8.
You do the math from there are get -2 1/8, I think...
Hope this helped!