Well I think the best way for you to make cash would be to do blue drags or something dunno what they are called forgot

. But these take 85 dunging so you would need to get that up a bit
Is there no way you can use a old dung script or buy some leeching here off sythe?
Those blue dragons are frost dragons. Also, leeching off other people on Sythe is out of his price range at the moment.
If I we're you, I would suggest trying out PvM (definitely a good way to make money from next to nothing)
First off, I'd suggest investing the remainder of your money in decent equipment (barrows armor, abbysal whip, warrior ring, ect..) and supplies (such as prayer potions, food, and so on)
If your having troubles thinking of things to kill, here are a few I would recommend.
Barrows - An oldie but a goodie, and best of all it can be done with little to no starting cash. Grab a slayer staff/polypore staff + ahrims and a spec weapon ( a dds will work ) and you will have no problem making several runs.
Slayer - After the effigy nerf many people are stopping to slay, but it is still a decent way to make a little bit of cash + gain some experience.
Revenants - Although this method of cash is dangerous and more inconsistent than the others, it can be quite profitable (vesta, statius, ect..)
Dragons - Killing dragons is one of the oldest methods of making some quick cash, and you make anywhere from 100k - 3m an hour depending on the type of dragon you are killing (green, blue, frosts, mith, ect..)
God Wars - If you have not done it before, it may intimidating, but with your stats + some decent equipment you could easily manage a couple of bandos kills.
Corporeal Beast - If you have access to it, I'd suggest investing in ganodermic + a zamorakien spear (can be solo'ed without overloads, maxed combat, turmoil, ect..) although I would suggest bringing along a friend.
If your not a fan of PvM you could alway's try a method from one of the videos below (few requirement + an easy way to make some quick cash)
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Goodluck ^_^