COST

Last Tuesday a trucker paid $155.76, including 10 percent state and federal taxes, for diesel fuel. What was the price per gallon for the fuel if the taxes are excluded?

(1) The trucker paid $0.118 per gallon in state and federal taxes on the fuel last Tuesday.

(2) The trucker purchased 120 gallons of the fuel last Tuesday.

x - price per gallon
n-no of gallons

Rephrase the question-

xn=price paid for n gallons (not including taxes)

xn + 0.1xn = 155.76

we need x

1) taxes paid per gallon = 0.1xn/n = 0.1x = 0.118. x can be found

SUFFICIENT

2) n= 120. Substituting in maind equation you can get x.

SUFFICIENT
Hence, D

If x = number of gallons and n = price/gallon before taxes, how do i start from this equation : x(1.1n)= 155.76 ?

I know hoe to use this equation to confirm that B is sufficient, but unable to do so for A.

Thanks for the effort

Are you asking me how to arrive at that equation? Or how to use that equation to prove A?

If its the latter,

A says:
The trucker paid $0.118 per gallon in state and federal taxes on the fuel last Tuesday

Question : given taxes is 10% on original cost before taxes so = 0.1 nx

so for 1 gallon it is 0.1nx/n = 0.1 x

According to A, 0.1x=0.118.

You get the value of x, which is the value of price per gallon before taxes.

Note, you switched the notations I used in my solution.

i have used
n= no of gallons,x= price per gallon before taxes.

although doesn't matter but jsut wanted to clear up so it doesn't confuse.

Let me know if this helped

I understand now. Thank you