Okay. First off, let’s solve for the first two sides, since they are the same length. Set it up like this: 8x - 4 = 5x + 11. Subtract 5x from both sides to get 3x - 4 = 11. Next, add 4 to both sides to get 3x = 15. Now, divide each side by 3 to isolate the x and you get 5. Let’s plug in the values. 8 * 5 = 40 - 4 = 36. 5 * 5 = 25 + 11 = 36. There. x = 5. Now, let’s plug the 5 in to the other formula. 5 * 4 = 20. 20 - 2 = 18. There. BC is 18 units long.
