Answer :
SOLUTION
In this question, we are meant to evaluate:
[tex]\begin{gathered} \frac{xy}{x\text{ + y}}\text{ when x = -6 and y = 13} \\ \\ \text{put the value of x = 6 and y = 13 into the equation, we have that:} \\ \\ \frac{6(\text{ 13)}}{6\text{ + 13 }}\text{ = }\frac{78}{19}\text{ = 4 }\frac{2}{19} \end{gathered}[/tex]