Suppose that the weight (in pounds) of an airplane is a linear function of the amount of fuel (in gallons) in its tank. when carrying 18 gallons of fuel, the airplane weighs 1999 pounds. when carrying 46 gallons of fuel, it weighs 2153 pounds. how much does the airplane weigh if it is carrying 58 gallons of fuel?

The period of a pendulum varies directly as the square root of the length of the pendulum and inversely as the square root of the acceleration due to gravity. find the period when the length is 144 cm and the acceleration due to gravity is 980 cm per second squared, if the period is 7pi seconds when the length is 289 cm and the acceleration due to gravity is 980 cm per second squared.