1 2 3 4 5 6 7 8 9 10 11 -1 Sales Mon Tue Wed Thur [Graphs generated by this script: initPicture(-2,7,-1,11);axes(10,1,1);text([-1,5],'Sales','left');fill='blue';rect([1,0],[2,1]);rect([2.5,0],[3.5,7]);rect([4,0],[5,2]);rect([5.5,0],[6.5,6]);text([1.5,0],'Mon','below');text([3,0],'Tue','below');text([4.5,0],'Wed','below');text([6,0],'Thur','below');fill='white';stroke='white';rect([-.5,-2],[.5,-.1]);] The plot above shows the number of computers a store sold the first four days of this week. How many computers did they sell altogether these four days