I need help with this equation please

Acar started driving from city a to city b, distance between which is 620 miles, at a rate of 60 mph. two hours later a truck left city b and started moving towards city a at a rate of 40 mph. how many hours after the truck's departure will the two meet?

Two sides of a right triangle measure 2 units and 4 units. what is the area of the square that shares a side with the third side of the triangle?

What 620000 divided by 10 to the third power