Amy's car holds at most 18 gallons of gas. Now it has 6 gallons. Use pencil and paper. Explain how to find the amount of gas she needs, in liters, to fill the gas tank.

10 gallons

Amy's car's maximum capacity to hold gas = 19 gallons

present amount of gas  = 9 gallons

As the car's capacity is 19 gallons and present amount in tank is 9 gallons, so we can fill it as much as so that the amount in tank becomes 19 gallons.

let assume she fills x gallons

then x gallons and 9 gallons present earlier should be equal to 19 gallon, as the tank can not hold more than that.

lets write it mathematically

x + 9 = 19

subtracting 9 from both side

x + 9 - 9 = 19 - 9

=> x = 10

maximum area = xy = (16)(32) = 512 ft2

to maximize the area of the garden, the side of the fence parallel to the side of the house should be 32 ft long, and the other two sides should both have length 16 ft.'

source

twenty-six miles over two gallons because the proportion for the original 13 miles to one gallon would be written 13/1 and, doing the same thing to the top and bottom, i multiplied by 2 and got 26/2