A line cuts two concentric circles. The lengths of chords formed by that line on the two circles are 4 cm and 16 cm. What is the difference (in cm2) in squares of radii of two circles?
A bus moves at a speed of 84 km/hr after repairing and moves at a speed of 56 km/hr before repairing. It covers 2x distance in 8 hours after repairing.How much time (in hours) will it take to cover x distance before repairing?