Please help! I dont understand this, I will give 15 points!

Answer:
Step-by-step explanation:
common denominator is the multiplication of the two denominator or the least common multiple of the two
common denominator 24 10 12
13/24 +7/12 ☑ ☑
7/6+(-5/12) ☑ ☑
-3/4+(-2/3) ☑ ☑
5-7/10 ☑ ☑
1/8 - 5/3 ☑ ☑
3/2 - 4/5 ☑ ☑