The following information for advertising and sales has been established over the past six months:
?????? Month????????????????????????? Sales revenue??????????????? ????? ?Advertising expenditure
??????????????????????????????????????????????? $'000???????????????????????????????????????? $'000
????????? 1??????????????????????????????????? 155????????????????????????????????????????????? ?3
??????????2??????????????????????????????????? 125???????????????????????????????????????????? ?2.5
????????? 3??????????????????????????????????? 200?????????????????????????????????????????????? 6
????????? 4??????????????????????????????????? 175???????????????????????????????????????????? 5.5
????????? 5????????????????????????????????????150???????????????????????????????????????????? ?.5
???????? ?6????????????????????????????????? ? 225??????????????????????????????????????????? ?6.5
Using the high-low method which of the following is the correct equation for linking advertising and sales from the above data?