Charlie entered an elevator and ride up 10 floors and then down 2 floors before realizing he had not pressed the button for floor 1. he then pressed the button for floor 1 and rode down 14 floors and exited the elevator on floor 1. on which floor did he begin?

Floor 7

Step-by-step explanation:

He entered the elevator on floor x.

Then he rode up 10 floors. Now he is on floor x + 10.

Then he rode down 2 floors. Now he is on floor x + 10 - 2 = x + 8.

Then he pressed the Floor 1 button and rode down 14 floors to Floor 1. Now he is on floor x + 8 - 14 = x - 6 which is the same as Floor 1.

Floor x - 6 is the same as Floor 1, so we get the equation:

x - 6 = 1

Add 6 to both sides:

x = 7

Since we let x be the floor number he entered the elevator in, he entered the elevator on Floor 7.