Did I do this right?

What is the product of 1.7 × 10–13 and 3.5 × 1025? (5 points) 1.8 × 1012 2.06 × 1012 3.5 × 1012 5.95 × 1012

According to modern science, earth is about 4.5 billion years old and written human history extends back about 10,000 years. suppose the entire history of earth is represented with a 10-meter-long timeline, with the birth of earth on one end and today at the other end.

Which represents the solution set of the inequality 5x-9 < 21? a. x < 12/5 b. x > 12/5 c. x > 6 d. x < 6