Okay, I was thinking of numbers for their values and not the shapes. And yes, I think the third one seems like bit of a stretch, I was thinking this in terms of sum of the (other) numbers too. I was kinda close too when I tried to start and end with eight based on the last hint too but was still going wrong with thinking the second would be half of the number and not visually half of it. And obviously third one too but would have come to correct one on this since I tried to loop through the whole thing.
So basically my solution of 2185 was completely correct but just thinking from different angle. So it's kinda like if you give a math student a test where they need to solve a quadratic equation but only accept one of the answers.