Name numbers that’s round to 140,000 or 240,000 when rounded to the nearest ten thousand

Can someone me out here and the tell me the greatest common factor

Starting at home, emily traveled uphill to the hardware store for 606060 minutes at just 666 mph. she then traveled back home along the same path downhill at a speed of 121212 mph. what is her average speed for the entire trip from home to the hardware store and back?

I’m really confused and need to learn this