Question 19
Given $5\diamond3=6$, $3\diamond5=-10$ and $9\diamond6=18$, find the value of $7\diamond4$.
The source supplies examples but no definition of the operation. A unique value is not guaranteed. State a rule, verify all three examples and evaluate the requested expression under that rule; explain whether the value is uniquely determined. This response requires manual review. The diamond denotes the same operation symbol as in the source.

The source supplies examples but no definition of the operation. A unique value is not guaranteed. State a rule, verify all three examples and evaluate the requested expression under that rule; explain whether the value is uniquely determined. This response requires manual review. The diamond denotes the same operation symbol as in the source.
