Let the number of bottled water be x and number of medical kits be y.
It is given that the bottled water weighs 20 pounds per container and measures 1 cubic foot and the medical kits each weigh 10 pounds and measure 2 cubic feet.
Also the plane can carry 90000 pounds so it follows:
[tex]\begin{gathered} 20x+10y=90000 \\ 2x+y=9000\ldots(i) \end{gathered}[/tex]The plane can carry 6000 cubic feet so it follows:
[tex]x+2y=6000\ldots(ii)[/tex]Multiply equation (i) by -2 to get:
[tex]-4x-2y=-18000\ldots(iii)[/tex]Add (ii) and (iii) to get:
[tex]\begin{gathered} x-4x=6000-18000 \\ -3x=-12000 \\ x=\frac{-12000}{-3} \\ x=4000 \end{gathered}[/tex]Substitute the value x=4000 in (i) to get:
[tex]\begin{gathered} x+2y=6000 \\ 4000+2y=6000 \\ 2y=6000-4000 \\ 2y=2000 \\ y=\frac{2000}{2} \\ y=1000 \end{gathered}[/tex]Hence each plane can carry 4000 bottled water and 1000 medical kits.
