The sum of the digits of a two-digit number is 14. If the numbers are reversed, the new number is 18 less than the original number. Find the original number.

Question

I know Ana asked this question, but i don't understand how to get the equations.

Answer 1

I thought Damon did a pretty good job of explaining this question before

Ok, here is my approach, perhaps it will make sense to you.

Let the unit digit of the original number be x
Let the tens digit by y
then the original number was 10y+x

We were told the sum of the digits is 14, so
x+y=14, this is your first equation

the number reversed would be 10x+y
but this is 18 less than the original number, so....

10x+y + 18 = 10y+x , (since it was 18 less, I added 18 to make them "equal")

9x - 9y = -18
x-y = -2 , this is your second equation.

I will leave it up to you to solve them

Answer 2

I don't understand how to get the second equation

Answer 3

would you agree that according to my definition, the original number is 10y+x and the number reversed is 10x+y ???

your problem stated "the new number is 18 less than the original number." which translates into

10x+y < 10y+x by 18, so I added 18 to the "smaller" side to make them "equal", thus

10x+y + 18 = 10y+x
surely you can see how that simplifies to x-y=-2

Answer 4

So the answer would be 86?

Answer 5

Do the digits of 86 add up to 14?
Is 68 less than 86 by 18 ??