Let's assume the number consists of two digits. Let the tens digit be represented as x and the ones digit as y.
So, the number can be written as: Number = 10x + y
Given:
The sum of the digits is 8. This means: x + y = 8
If 18 is added to the number, the digits get interchanged. This gives us the equation: (10x + y) + 18 = 10y + x
Now, let's solve the system of equations step by step.
Step 1: Simplify the second equation.
(10x + y) + 18 = 10y + x
This simplifies to:
10x + y + 18 = 10y + x
Now, move all terms involving x and y to one side:
10x - x = 10y - y - 18
9x = 9y - 18
Divide both sides by 9:
x = y - 2
Step 2: Substitute into the first equation.
We know x + y = 8. Substitute x = y - 2 into this equation:
(y - 2) + y = 8
2y - 2 = 8
2y = 10
y = 5
Step 3: Find x.
Now that we know y = 5, substitute this value into the equation x = y - 2:
x = 5 - 2
x = 3
Step 4: Construct the number.
The tens digit is 3 and the ones digit is 5. So, the number is 35.
Thus, the number is 35.
Answer: b) 35