basically you need to make the denominator (whats on the bottom) the same, lets take the first one for example
2 3/4, lets put this all over 4 for the same denominator.
2=8/4, and then add this to 3/4 to get 11/4.
the second part will work the same way,
start by making 1 into 8/8. add this to 1/8 to get 9/8
now we have to add 11/4 and 9/8. to do this, you have to find the smallest multiple between the two (for example: between 6 and 4 it would be 12, since 4*3= 12, and 2*6=12)
now, the smallest common multiple between 4 and 8 would just be 8
11/4= 22/8, since you multiply the bottom and top by the same amount so it still equals 11/4, but your denominator will now be 8.
now you can subtract. 22/8- 9/8= 13/8
final answer: 13/8
try the rest yourself since this is important for later math, hoped this helped :)