Answer: X=50
Explanation:
Data: 4 less than half of a number(x) is 21
Step one, make an equation
(x/2)-4=21
The reason for this is that since we know that 21 is 4 less than half the number(x) we can assume that dividing x by 2 will get half of it and by subtracting 4, we can get 21 which why it equals 21. By having it in an equation, it makes it easier to solve.
Step two, Start isolating x by adding 4 on both sides
(x/2)-4+4=21+4=(x/2)=25
The reason for this is that we have to find what x is which is done by isolating it. So if you add 4, you get rid of the -4 which helps isolate x and what you do to one side, you do to the other so you add 4 to 21 as well
Step three, multiply by 2 on both sides
(x/2)x2=25x2=X=50
The reason for this is that /2 is next to x so to isolate you have to get rid of it by multiplying by 2 and since what you do to one side you do to the other, you multiply 25 by 2 to get 50.
Answer: X=50
I hope this helps!