Lidia plans an experimental investigation to see how the thickness of a lens affects the point where a beam of light is focused. She plans to shine light through a lens and measure the distance to a screen that is placed where the beam focuses. What are the controls in Lidia’s investigation?

Simba travel agency arranges trips for climbing mount kilimanjaro. for each trip, they charge an initial fee of \$100$100 in addition to a constant fee for each vertical meter climbed. for instance, the price for climbing to the shira volcanic cone, which is 30003000 meters above the base of the mountain, is \$400$400. let f(d)f(d) denote the fee of a trip ff (measured in dollars) as a function of the vertical distance climbed dd (measured in meters). write the function's formula. f(d)=