Answer: m=n=3
Step-by-step explanation:
Reflecting across the y=0, in other words, the x-axis, means
[tex](x,y) \longrightarrow (x,-y)[/tex]
So, [tex]p(m,5-n) \longrightarrow p'(m,n-5)=p'(2m-3, 2n-8)[/tex]
This gives us the system
[tex]m=2m-3 \longrightarrow \boxed{m=3}\\\\n-5=2n-8 \longrightarrow \boxed{n=3}[/tex]