Help me please with complete solution and clear explanation. Please briefly explain it thank you.

Reference: https://drive.google.com/folderview?id=1jT0hecxoRkKhTuKxSaOwZgzuEe1v2Hfn

WRITTEN WORK Directions: Read the items carefully and choose the letter of the best answer. 1. What kind of variation is the statement, "x varies directly as y and inversely as z"? a) Direct Variation c) Joint Variation b) Inverse Variation d) Combined Variation 2. In the equation z = kxy, which denotes the constant of variation? a) k b) x c) y d) z 3. As the number of pens you buy increases, the amount you have to pay also increases. How does the number of pens vary with the amount to be paid? a) Directly b) Inversely c) Jointly d) Indirectly _4. Which of these quantities are inversely related? a) Side of a cube and its surface area b) Diameter of a circle and its circumference c) The number of tickets sold and the gross sale d) Distance travelled by the car and the gas left in the tank 5. The time it takes to hear thunder varies directly with the distance from the lightning. What do you mean by this statement? a) As the distance from the lightning increases, so does the time it takes you to hear the thunder. b) As the distance from the lightning increases, the shorter the time it takes you to hear the thunder. c) The nearer you are from the lightning, the louder you hear the thunder. d) The distance of the lightning has no effect in the time it takes to hear the thunder