Answer:
Explanation:
The process seems to be largely one of trial and error. We can get (signed) sums of 0, 1, 2, 3, 6, 7, 9, 11, 12, 13, 14, 15, 18, and more. But none of these obviously leads to a value of 4. Products don't seem to get there, either. So we found some ratios that could help achieve a value of 4.