If 6x + 4 = 11x - 21, what is the value of x?

X=5

Explanation: 6x + 4 = 11x - 21
1). Subtract 4 from both sides and you will get 6x = 11x -25.
2). Subtract 11x from both sides and you should get -5x = -25.
3). Divide the -5 with -25 to get x alone and you should get X=5!

Check your work:
6(5) + 4 = 34 & 11(5) - 21 = 34
34=34.

Maybe the answer is 20mm. all i really did was just multiply, which is obvious.