Khim’s brother is six years younger than him. 18 multiplied by 1/3 (0.33) is 5.94 but since no one can exactly be 5.94 years old, round it to 6. The reason that you would multiply is because it makes the number smaller, which is exactly what he problem is asking for. Do the same process with the age of 36 instead of 18.
If I understand the question correctly, Khim’s brother was a third of Khim’s age when Khim was 18. 1/3(18) = 6. 18-6 =12. No matter what, Khim’s brother will be 12 years younger than Khim. So when Khim is 36, his brother is 24.
