We have the next variables
x = speed of the boat in still water
y = speed of the current
(x-y) = Upstream speed
(x+y) = downstream speed
So we have the next equations for the distance
[tex]\begin{gathered} 6\mleft(x-y\mright)=408 \\ \end{gathered}[/tex][tex]\begin{gathered} 9(x+y)=882 \\ \end{gathered}[/tex]We simplify each equation
[tex]\begin{gathered} x-y=68 \\ x+y=98 \end{gathered}[/tex]we sum both equations
[tex]\begin{gathered} 2x=166 \\ x=\frac{166}{2} \\ x=83 \end{gathered}[/tex]Then we calculate the y
[tex]\begin{gathered} y=98-x \\ y=15 \end{gathered}[/tex]x = speed of the boat in still water=83 km/hr
y = speed of the current 15 km/hr
