So half a number means 1/2(x)
21 less than half a number is 1/2(x)-21
And four times a number means 4x
So if we put it together the equation would be: 1/2(x)-21=4x
So we just solve for x
Subtract .5 on each side to get -21= 3.5x
Then divide 3.5 from both side and the result would be 6
X=6
