8 A firm selling CDs finds that the number sold (N thousand) is related to the price (£P) by the formula 6P+N = 90. a Draw the graph of N against P for 0≤N≤90 (the vertical axis should be the P axis, and the horizontal axis should be the N axis). b Use your graph to find the price when 30 000 CDs are sold. c Use your graph to find the number sold if the price of a CD is set at £8. d Use your graph to find the price if 90 000 CDs are sold. Is this a sensible value?
