What is 4.5 percent of 639.87 - step by step solution

To get the solution, we are looking for, we need to point out what we know.

1. We assume, that the number 639.87 is 100% - because it's the output value of the task.
2. We assume, that x is the value we are looking for.
3. If 639.87 is 100%, so we can write it down as 639.87=100%.
4. We know, that x is 4.5% of the output value, so we can write it down as x=4.5%.
5. Now we have two simple equations:
1) 639.87=100%
2) x=4.5%
where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:
639.87/x=100%/4.5%
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for what is 4.5% of 639.87

639.87/x=100/4.5
(639.87/x)*x=(100/4.5)*x       - we multiply both sides of the equation by x
639.87=22.222222222222*x       - we divide both sides of the equation by (22.222222222222) to get x
639.87/22.222222222222=x
28.79415=x
x=28.79415

now we have:
4.5% of 639.87=28.79415