How to solve 55% of 600 with a visual

1. We assume, that the number 600 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 600 is 100%, so we can write it down as 600=100%. 
4. We know, that x is 55% of the output value, so we can write it down as x=55%. 
5. Now we have two simple equations:
1) 600=100%
2) x=55%
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:
600/x=100%/55%
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 55% of 600

The linear equation is: y=ax+b