tolong bagaimana caranya yg benar?

[tex]k = 2p + 2l \\ = 2(3x - 4) + 2(x + 2) \\ = 6x - 8 + 2x + 4 \\ = 8x - 4[/tex]
[tex]k = 8x - 4 \\ 36 = 8x - 4 \\ 36 + 4 = 8x \\ 40 = 8x \\ x = \frac{40}{8} = 5[/tex]
[tex]p = 3x - 4 = 3(5) - 4 = 15 - 4 = 11[/tex]
[tex]l = x + 2 = 5 + 2 = 7[/tex]