Arocket travels west 450 km in 3.75 minutes(225 sec). what is the velocity of the rocket in km/s?

If 20% of a number is 35, what is 50% of that number?

In a tutoring session, 2/3 of an hour was spent reviewing math problems. adelina attended 3/4 of the tutoring session. how much time did adelina spend at the tutoring session?

Aliter of water contains about 3.35 x 10^25 molecules. a certain river discharges about 2.9x 10^8 l of water every second. about how many molecules does the river discharge every minute? write your answer in scientific notation