Hello, it appears you did not provide an image that was supposed to be included in order to help answer your question, so I'm afraid I cannot assist you without seeing it. If you supply the necessary photo, I would be more than happy to help you.
Any multiples of 4.5:1.5 would work because being proportional just depends on whether you can reduce to get the same answer of the first triangle. You could do anything like 9m and 3m or 27m and 9m