Question

A two-digit number is 5 times the sum of its digits. If 9 is added to the number, its digits are reversed. Find the number​

Answer 1

Answer:

The number = 45

Step-by-step explanation:

Let the 10s digit = x

Let the units digit = y

10*x + y = 5(x + y)                        Start here: remove the brackets

10*x + y + 9 = 10y + x                   Subtract y and 10x from both sides

Using the first equation

10x + y = 5x + 5y

5x + y - 5y = 0

5x - 4y = 0

5x = 4y

y = 5/4x

From the second equation

9 = 9y - 9x

1 = y - x           Substitute y = 5/4 x

1 = 5/4x - x

1 = 1/4  x

x = 4

y = 5/4 * 4

y = 5.