दोन शहरांमधील अंतर 50 किमी/तास या वेगाने 7 तासांत कापले जाते. वेग (किमी/तास) किती वाढवावा जेणेकरून प्रवासात 2 तासांच्या वेळेची बचत होईल?
The distance between two towns is covered in 7 hours at a speed of 50 km/h. By how much should the speed (in km/h) be increased so that 2 hours of travelling time will be saved?
70
20
30
40