Question

a number machine takes any number put into it, multiplies it by 3 and then subtracts 2. reuben put a number into the machine. he took the new number that came out and put that number back into the machine. He took the new number that came out and put that back into the machine. the number that came out this time was 271. what number did reuben originally put into the machine?

Reiny already answered this question but I didn't get the explanation
Help

Answer 1

first number ----> machine ----> 2nd number ---> machine ---> 3rd number ----> machine ----> 4th number = 271

Machine basically multiplies the number by 3 and subtracts 2.
So we work backwards. 271 + 2 = 273. Divide it by 3 to get the 3rd number, 91.
Do the same thing 2 more times. 91 +2 = 93.
93/3 = 31. 31 + 2 = 33. 33/3 = 11. So the original number is 11. Check work

11 * 3 - 2 = 31. (2nd number) 31 * 3 - 2 = 91. (3rd number) 91 * 3 - 2 = 273 -2 = 271. TADA! we win :P