First one: First let's factor the numerator and denominator
Numerator z^2 (z+1)(z+2)
Denomin (z+1) (z)(z+3)
Second determine what values of z are not allowed (those that would make either denominator = 0 are not allowed)
z = 0 or -1 or -3 are not allowed
Now cancel out the term (z+1) and you are left with
z^2(z+2) / z(z+3) Simplify (one more z will cancel out)
(z)(z+2) / (z+3) = (z^2 +2z) / (z+3)
Your second question is similar to the first (but remember ...when you divide by a fraction you flip it over and multiply) Remember to find the values of x which are not allowed in the denominators before you flip it