For question 1, you've made a good start. Try to rearrange the first equation, so you can work with one equation by substitution.
Hint: If we make one of the variables the subject, can we perhaps do something with it for the second equation. If you're still unsure, I'll walk you through it.
For question 2, all of the hard work has been done. You just need to substitute in L to the second equation to have an equation with one variable.
That is, whenever we see L in the second equation, we can substitute in 4W, instead, and work out what W is. After that, use the first equation and divide by 4 to find L.
If you're still unsure, I can walk you through it.