TRY TO SOLVE ATLEAST 1 PLEASE

a) Use Vieta's Theorem to solve the problems. The difference of the two solutions of x^2+19x+c=0 is 15. Find the solutions.

b) Use Vieta's Theorem to solve the problems.
The difference of the two solutions of x^2+19x+c=0 is 15. Find c.

c) One pipe can fill a pool in 9 hours. Another pipe can fill the pool in 6 hours. How long would it take them to fill the pool if they were working together?

d)When two pipes fill a pool together, they can finish in 5 hours. If one of the pipes fills half the pool then the other takes over and finishes filling the pool, it will take them 18 hours. How long will it take each pipe to fill the pool if it were working alone?