Calvin went cycling in San Francisco, which is extremely hilly. He can pedal up a hill at a speed of 12 mph, and down a hill at a speed of 36 mph. If he went up and down a hill (back to the same point), what is his average speed (in mph) for the entire journey?
In a park, the ratio of red roses to white roses is . If there are 30 red roses, how many white roses are there?
If it takes 33 minutes for a water faucet to fill up a tub, how many minutes will it take the water faucet to fill up of the tub?
A grocer has a stack of apples and a stack of oranges. After arranging them in neat rows, he realizes that he has 4 apples for every 3 oranges. Given that he has 168 apples, how many oranges does he have?
If a vehicle can travel at 68 kilometers per hour, how far (in kilometers) can it go in 225 minutes?