80 is what percent of 1989 - 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 1989 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 1989, so we can write it down as 100%=1989.
4. We know, that x% equals 80 of the output value, so we can write it down as x%=80.
5. Now we have two simple equations:
1) 100%=1989
2) x%=80
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%=1989/80
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 80 is what percent of 1989

100%/x%=1989/80
(100/x)*x=(1989/80)*x       - we multiply both sides of the equation by x
100=24.8625*x       - we divide both sides of the equation by (24.8625) to get x
100/24.8625=x
4.0221216691805=x
x=4.0221216691805

now we have:
80 is 4.0221216691805% of 1989