Question

Two airplanes start at the same time and fly toward each other from points 1000 km apart at rates of 420 km/h and 330 km/h. After how many hours will they meet?

Answer 1

suppose the planes will meet after x hours of flying.

the first plane will cover 420x miles  the second one will cover 330x miles

so the total distance covered by both planes will be 420x + 330x = 1000 miles

that is. 750x = 1000   x = 1000/750 = 1.33 hours.  or  1hour.  19min. and. 48 secs