If the difference between a number and 21 is divided by2, the result is 4 times the number. What is the number

(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