Given in the question:
1) Earnings money each week = Earning is an addition to one's money, thus, we can say that this situation is a POSITIVE Slope.
2) Withdraw money each month = Widthrawing is a deduction to one's money, thus, we can say that this is a NEGATIVE Slope.
3) Depositing your paycheck = Depositing is adding money to your account, thus, we can say that this situation is a POSITIVE Slope.
4) A plane landing = A plane landing has its speed slowly decreasing until its speed gone to zero, thus, we can say NEGATIVE Slope.
5) The number of students is decreasing each year = A decreasing number of students is a deduction to the population of students, thus, we can say that this is a NEGATIVE Slope.
6) A plane taking off = A plane taking off has its speed accelerating, thus, we can say that this situation is a POSITIVE Slope.