Can someone i really don't get this one

An appliance salesman sets a goal to sell an average of 6 appliances per day for the first two weeks of his new job. the dot plot shows the number he sold each day during the first 13 days. what is the minimum number of appliances he must sell on the 14th day in order to reach his goal? a) 5 b) 6 c) 7 d) 8

Ineed with number 17 i don’t get it at alll

Factor x2 – 8x + 15. which pair of numbers has a product of ac and a sum of what is the factored form of the