Assume Nail Mania advertises in the local newspaper. Each day it advertises costs $100. Over the past several months, Nail Mania has conducted market research and developed the following information Number of days advertised per week Number of customers per week 0 100 1 200 2 290 3 355 4 375 5 390 6 400 7 400 If the net revenue (payments less cost of goods sold) is $5, how many days of advertising should Nail Mania buy each week?