Let's take any edge length l. The diagonal has length

. In our case it's
Answer:
12
Step-by-step explanation:
To solve the problem, you have to leave the x alone,
To do so, you have to add 84 on each side
12x = 4x + 96
Then, subtract 4x on each side,
8x = 96
Then divide each side by 8, so
x = 12
Hope it helps!!
Let me know if I'm wrong or you need help on anything else!!
Also, if you're okay with it, can you plz make be brainliest?
If you are looking forward to adding them together you will get 145. Just need to know if this questions had options?