Can someone help to solve question 6 a) and b)

Which of the following is the correct ratio for converting kilograms to grams

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

Tyler enjoys the fish so much that after his birthday his family decides to take him to a famous aquarium a tank at the aquarium is similar to his tank with the scale factor of 8 how many times greater is the volume of the tank at the aquarium than the volume of tyler tank