Question

The sum of the digits of a two-digit number is 5. If nine is subtracted from the number, the digits will be reversed. Find the number. If the numbers 32, What's the equation?

Answer 1

Explanation:

Hello,

let's note a and b the two digits, the number is then a*10+b

and the digits in revers mode give b*10 + a so we can write

(1) a + b = 5

(2) 10a+ b - 9 =10b + a

From(1) I get b = 5-a

I replace in (2)

10a + 5 - a - 9 = 10(5-a) + a = 50 - 10a = a = 50 - 9a

9a - 4 = 50 - 9a

18a = 50 + 4 = 54 so

a = 54/18 = 3

and then from (1) b = 5 - 3 = 2

So the number is 32