Well str exp is at max around 13k/hr with 1 attack. With that being said; 86 strength requires 3,597,792 exp. so to determine how many hours it would take to get 86 strength we do 3,597,792 divided by 13,000. We get 277 hours (Rounded up from 276.753231). so to determine days we take 277 hours and divide that by 24. we get 11.5 (rounded down from 11.5416667) days. Just so you know (since you seem relatively unintelligent anyways) there are only 7 days in a week. And that is at botting 24/7 which is nearly impossible to do and requires 24/7 hours of baby sitting. and also if you can bot 24/7 for 11.5 days without being banned you must be a god.However, simply put, your logic is flawed. (this isn't taking into account the lower levels due to the fact that you do not gain 13,000 xp/hr at lower levels. so in theory it would take even longer.)
Slayer is by hand. And i listed the quests done; RFD with mith gloves (since it already has stats) wont take long at all. If its so easy to make go ahead and do it in a week. Have fun getting 55 slayer at 1 attack and 1 defense. Since you're superman it must only take you 2 hours.