Okay, let’s tackle this. So Hefi has 6 months of experience in operation planning and controlling at KALOG. In Indonesia, the average hourly rate for an operation planning and controlling specialist is around IDR 1,000,000 - IDR 2,000,000 (USD 70-140) per month. Considering his experience, I'll estimate his hourly rate to be around IDR 500,000 - IDR 1,000,000 (USD 35-70) per hour. Since the problem doesn't specify the industry or location, I'll use the lower end of the range to be conservative. Therefore, I estimate Hefi's hourly rate to be around USD 40.