The first one cannot be factored further, since there are no common factors amongst the terms.
The second one can be written as this
Since there are 2 terms that have a 5 in them, you can factor out a 5
If you distribute the 5, you will get 5y-15
the 3rd problem can be written as
Where the 5 is factored out
The fourth is similar, but the common term is x. So factor out an x
If you distribute the x you get x^2+2x.