Could someone me , also it would be super of you if you also showed the work so i can figure out the rest of the problems.

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

1. We assume, that the number 321 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 321 is 100%, so we can write it down as 321=100%. 
4. We know, that x is 642% of the output value, so we can write it down as x=642%. 
5. Now we have two simple equations:
1) 321=100%
2) x=642%
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:
321/x=100%/642%
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 642% of 321

321/x=100/642
(321/x)*x=(100/642)*x       -we multiply both sides of the equation by x
321=0.15576323987539*x       - we divide both sides of the equation by (0.15576323987539) to get x
321/0.15576323987539=x 
2060.82=x 
x=2060.82

now we have: 
642% of 321=2060.82

I hoped this helped!