Craig charges $25 for each lawn he mows. He also charges $25 for each dog he walks. Last week he mowed 6 lawns and walked some dogs for a total earnings of $275. Let x represent the number of dogs Craig walked

List x1, x2, x3, x4 where xi is the left endpoint of the four equal intervals used to estimate the area under the curve of f(x) between x = 4 and x = 6. a 4, 4.5, 5, 5.5 b 4.5, 5, 5.5, 6 c 4.25, 4.75, 5.25, 5.75 d 4, 4.2, 5.4, 6