So you first find a common denominator.
To do for 2/5 that you multiply the numerator and the denominator by 4.
The answer to that would be 8/20.
Then you do the same for 1/4.
You should get 5/20.
The equation for the rest of the problem is : 5 5/20 - 1 8/20
*REMEMBER never subtract the denominator
5 5/20 - 1 8/20= 3 7/20
Now if you got that correct then do:
3 7/20 - 1 8/20= 1 9/20
Now this is you last step:
1 9/20 - 1 8/20 = 1/20
Hope that cold help you☺