things were not as complicated when I was in middle school.
I hope this helps you
[20x^2/4x^2y]+[4xy^2/4x^2y]-[8y^2/4x^2y]
[5/y]+[y]-[4y/x^2]
1/4 trust me bro just took it
2 2/3 = [(2*3)+2]/3 =8/3
(8/3)/5=8/(3*5)=8/15
Consider such events:
A - slip with number 3 is chosen;
B - the sum of numbers is 4.
You have to count 
Use formula for conditional probability:
1. The event 
consists in selecting two slips, first is 3 and second should be 1, because the sum is 4. The number of favorable outcomes is exactly 1 and the number of all possible outcomes is 5·4=20 (you have 5 ways to select 1st slip and 4 ways to select 2nd slip). Then the probability of event is
2. The event 
consists in selecting two slips with the sum 4. The number of favorable outcomes is exactly 2 (1st slip 3 and 2nd slip 1 or 1st slip 1 and 2nd slip 3) and the number of all possible outcomes is 5·4=20 (you have 5 ways to select 1st slip and 4 ways to select 2nd slip). Then the probability of event is
3. Then
Answer: 
