In the first, let z+5=a. This makes the problem look a little less distracting. We can always replace the z+5 after the end. So... How would you factor...

It would look like this

now if I put z+5 back in...

And you can simplify further.

In the second problem, try putting a=3x-4, and b= 5x-1. Then factor and replace like the last problem.