How do you do 18-21 i don’t understand it

What are the relative frequencies, to the nearest hundredth, of the rows of the two-way table? group 1: a 15 b 45 group 2: a 20 b 25

What is the number 321,000,000 in scientific notation? also what is the number? ?

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