please answer this problems. thank you.

Directions: Solve the following problems. Write your solutions in your activity notebook or answer sheet. 1 . The function below gives the concentration of the saline solution after adding the x milliliters of 0.5% solution to 100 mL of 2% solution. f ( x ) = 100(0.02) + x(0.005) 100 + x How many ml of the .5% solution must be added to have a combined concentration of 0.9%? 2. A plumber and his assistant finished a job together in 4 hours. The job would have taken the plumber 6 hours if he was working alone. How long would the job have taken the assistant if he was working alone? 3. A water tank is emptied through two drains in 50 minutes. If only the larger drain is used, the tank will be empty in 85 minutes. How long would it take to empty if only the smaller drain is used? 4. Working together, Tom and Jerry painted a fence in 8 hours. Last year, Tom painted the fence by himself. The year before, Jerry painted it by himself, but took 12 hours less than Tom took. How long did Tom and Jerry take, when each was painting