Question

Find the value of x in 3x + 4y = 12 and 9x - 4y = 24.​

Answer 1

x=3

Explanation:

we first write both equations:

`3x + 4y = 12 \\ 9x - 4y = 24`

then we add the Left hand sides from both, and compare to the Right hand sides from both:

`3x + 4y + 9x - 4y = 12 + 24 \\ 3x + 9x = 36 \\ 12x = 36 \\ x = 3`