Can someone please help me??

What is the common difference in the following arithmetic sequence 7,3,-1,-5

Chamberlin wants to bottle 1\8 of her apple cider. she pours the apple cider evenly among 6 bottles. what fraction of her apple cider will she put in each bottle? what expression could represent this situation?

Marco has $38.43 dollars in his checking account. his checking account is linked to his amazon music account so he can buy music. the songs he purchases cost $1.29. part 1: write an expression to describe the amount of money in his checking account in relationship to the number of songs he purchases. part 2: describe what the variable represents in this situation.