Basically in order to add fractions, you have to find the common denominator for both fractions.
For number 23:
The common denominator for 1/8 and 1/10 would be 40.
1/8 x 5/5 = 5/40
1/10 x 4/4 = 4/40
Then you would add those two fractions before simplifying it to it's simplest form.
5/40 + 4/40 = 9/40
9/40 cannot be reduced or simplified any further, so your answer to number 23 would be 9/40.
For number 24:
You basically do the same thing that you did for number 23 except the numbers are different.
Find the common denominator for the fractions.
6 1/4 and 7 2/3
Ignore the whole numbers for a second.
The common denominator for 1/4 and 2/3 would be 12.
1/4 x 3/3 = 3/12
2/3 x 4/4 = 8/12
Apply the whole numbers to your new fractions and add.
6 3/12 + 7 8/12 = 13 11/12
Once again, this cannot be reduced or simplified any further.
Your answer for number 24 would be 13 11/12.