The formula f 5280m can be used to convert a measurement of f feet to an equivalent measurement of m miles. if an airplane flies at 21,120 feet above the ground, how much is that in miles? 4 miles? 5.3 miles? 111,513,600 miles? 132,620,600 miles?

The formula is f = 5280m

It means that every mile has to be multiplied by 5280 to connvert into equivalen number of feet.

Now you need to find the number of miles equivalent to 21,120 feet, so solve the equation f = 5280m for m:

f = 5280m => m = f / 5280

=> m = 21120 / 5280 = 4

=> 4 miles