im 16 years old and weigh 120lbs. I used to smoke weed like if not almost everyday. But lately I havent. The last time I smoked was 3 days ago..and before that I was clean for a month. I have a pre employment drug test soon and want to know how long it takes to have my system clean. I know theres no way to clean it without the expensive detox systems. Any tips to pass it? How long til I can??