You say you want help but we cannot help you without knowing what kind of help you need. You can clarify that by showing what you do know about these problems, what you tried and where you ran into problems. In other words, show us what you have tried already.
Since you are new here, I will give you a hint for the first one- go ahead and ignoring the fact that and and unknow, try to solve the equations. If and were known numbers, how would you solve these equations? What about and would make that impossible?