Answer:
-3
Explanation:
With the information you have given, you can create a equation of,
6 - 5x = 21
Then, you just have to sort out the equation in order till you get the x alone.
First, subtract 6 from both sides,
- 5x = 15
Second, divide each side by - 5.
x = -3
Then, it done!!
Hope this helps!!
Let me know if I'm wrong...