Anyone know the answer to this question

Li buys supplies so he can make and sell key chains. he begins to make a profit only after he sells 4 key chains. what point on the graph makes the most sense in this situation?

Question 13 (1 point) jerome is starting a new job. his contract states he will earn $42,000 the first year, and will get a 4% raise per year. which function s(x) represents jerome's salary after a certain number of years, x?

Harry owes the bank money. to repay his debt, he paid $150 back to the bank each month. after 10 months, his remaining debt was $6900. what was the original amount of harry's debt? how long did it take harry to pay back his entire debt?