Please help what is the variable X? ​

If there are 3.281 feet in 1 meter, how many inches are in one centimeter

Cal's go cart has a gas tank with the dimensions shown below. he uses a gas can that holds 11 gallon of gas, to fill the go cart tank. 11 gallon = 231 inches^3 how many full gas cans will it take to fill the go cart's gas tank?

Use the quadratic function to predict f(x) if x equals 8. f(x) = 25x2 − 28x + 585