How can the Equations of Motion be used to calculate missing parameters?

[staceyw]

Can someone please explain what you are supposed to do when you are only give two or three of the things (eg displacement or time) when you need four, how are you supposed to work it out then? it seems to be very confusing!
I am really confused and need help! Thanks

 

[mbrmbrg]

I would suggest making a system with two different equations.