2.1 is what percent of 840 - 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 840 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 100% equals 840, so we can write it down as 100%=840.
4. We know, that x% equals 2.1 of the output value, so we can write it down as x%=2.1.
5. Now we have two simple equations:
1) 100%=840
2) x%=2.1
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:
100%/x%=840/2.1
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 2.1 is what percent of 840

100%/x%=840/2.1
(100/x)*x=(840/2.1)*x       - we multiply both sides of the equation by x
100=400*x       - we divide both sides of the equation by (400) to get x
100/400=x
0.25=x
x=0.25

now we have:
2.1 is 0.25% of 840