How to make money in runescape?

i am level 84 with 70 atk, 73 str, 64 def, 56 range, 47 mage, 85 wood cutting, 47 crafting, 40 theiving, 38 fletching, 53 mining, 40 smithing, 34 fishing, 32 cooking, 70 firemaking,4 farming, 33 hunter, 70 hp, 25 agility. and i dont have alot of money at all i need to know how to make like 20m under 2 weeks.