In a certain state, gasoline stations compute the price per gallon p, in dollars, charged at the pump by adding a 7 percent sales tax to the dealer's price per gallon d, in dollars, and then adding a gasoline tax of $0.18 per gallon. Which of the following gives the dealer's price per gallon d in terms of the price per gallon p charged at the pump? Choices.
A) d = p/1.07 - 0.18
B) d = p-0.25
C) d= (p-0.18)/1.07
D) d = p/1.25
E) d = (p-0.07)/1.18
Let dealers price (d) be 1. so adding 7% to dealers price is d+ 7% of d. i.e. 1 + 7% of 1 which is1 + 0.07. then add 0.18 to the value.   Now 1.07 + 0.18. this is now 1.25. you have the gasoline stations price (p) as 1.25 dollars.   Now sub 1.25 in the options to know which option gave you d = 1. d must equal 1 because you earlier picked 1 as the value of d in the question.   PS: always remember to start from E upwards.   Answer : d= (p-0.18)/1.07
<result>C</result>
In a certain state, gasoline stations compute the price per gallon p, in dollars, charged at the pump by adding a 7 percent sales tax to the dealer's price per gallon d, in dollars, and then adding a gasoline tax of $0.18 per gallon. Which of the following gives the dealer's price per gallon d in terms of the price per gallon p charged at the pump?