To simplify the fraction 9/18, you need to find the greatest common divisor (GCD) of the numerator (9) and the denominator (18). In this case, the GCD of 9 and 18 is 9.
Next, you divide both the numerator and the denominator by their GCD:
Numerator: 9 ÷ 9 = 1
Denominator: 18 ÷ 9 = 2
Now, you can rewrite the fraction:
9/18 = 1/2
So, the simplified form of 9/18 is 1/2.