The maximum value of $z=3 x+4 y$, subject to the constraints $x+y \leq 40, x+2 y \leq 60$ and $x, y \geq 0$ is

• A

  $130$
• B

  $120$
• Correct answer
  C

  $140$
• D

  $40$

Solution

$\begin{gathered}z=3 x+4 y \\ x+y \leq 40 \\ x+2 y \leq 60 \\ y=20 \\ x=20\end{gathered}$

Hence, the correct answer is option: 'C'.