SOLUTION: an aircraft uses 1680 gallons of fuel,the left tank used 45%,the right tank used 32.5%.how nuch was used by centre tank?

Question 228620: an aircraft uses 1680 gallons of fuel,the left tank used 45%,the right tank used 32.5%.how nuch was used by centre tank?
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Assuming that there are only three tanks, this means that the percentages must add to 100%. So let 'x' be the unknown percentage used by the center tank. Now add up the percentages and set them equal to 100 to get: .

Now solve for 'x' to get --->

So the center tank used 22.5% of the fuel. Now just multiply the total amount of fuel (1680) by 0.225 (the decimal representation of 22.5%): 1680*0.225=378

So the center tank used 378 gallons of fuel.