There are 3 marbles (yellow, blue, and green). you pick a marble and flip a coin. how many outcomes are possible?

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

Christina can paint 420 square feet in 105 minutes. which unit rate describes the scenario?

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a.m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?