What is 31 percent of 1290 - 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 1290 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 1290 is 100%, so we can write it down as 1290=100%.
4. We know, that x is 31% of the output value, so we can write it down as x=31%.
5. Now we have two simple equations:
1) 1290=100%
2) x=31%
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:
1290/x=100%/31%
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 31% of 1290

1290/x=100/31
(1290/x)*x=(100/31)*x       - we multiply both sides of the equation by x
1290=3.2258064516129*x       - we divide both sides of the equation by (3.2258064516129) to get x
1290/3.2258064516129=x
399.9=x
x=399.9

now we have:
31% of 1290=399.9