the sum of the digits of a certain two-digit number is 9. Reversing its digits decreases the number by 63. Find the number

Question

the sum of the digits of a certain two-digit number is 9. Reversing its digits decreases the number by 63. Find the number

Answer 1

Start by listing the numbers that add up to 9, then determine what 2-digit number they form.

 

9 + 0 = 9  --> 90

8 + 1 = 9 --> 81

          Reverse those digits = 18

          81 - 18 = 63

7 + 2 = 9 --> 72

          Reverse those digits = 27

          72 - 27 = 45

6 + 3 = 9 --> 63

          Reverse those digits = 36

          63 - 36 = 27

5 + 4 = 9 --> 54

          Reverse those digits = 45

          54 - 45 = 9