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.
