Carter plans to read 4 books during summer break: Charlottes web, Grasshopper summer, Diary of a Wimpy Kid, and Diary of a Wimpy kid 2. He wants to read diary of a wimpy kid 2 after diary of a wimpy kid. How many different orders can he read his books in?

I’m stuck on this i don’t understand.

Tabby sells clothing at a retail store, and she earns a commission of 6.25% on all items she sells. last week she sold a pair of jeans for $32.50, a skirt for $18.95, and 2 blouses for $14.95 each. what was tabby's total commission? a $4.15 b $5.08 c $81.35 d $348.60

What would be the reasons for lines 3 and 4? a. addition property; subtraction property b. addition property; solve c. substitution property; subtraction property d. substitution property; prove