(n-21)/2=4n is the equation
First, divide what is in the parentheses by 2
0.5n-10.5=4n
Then, multiply the whole equation by 2 so we have all whole numbers
n-21=8n
Move N so that it is with 8n
7n=-21
Divide 21 by 7
n=-3
Solution: The number (n) is equal to -3