In the Blackhawk landslide in California, a mass of rock and mud fell 460 m down a

Question:

In the Blackhawk landslide in California, a mass of rock and mud fell 460 m down a mountain and then traveled 8 km across a level plain on a cushion of compressed air. Assume that the mud dropped with the free-fall acceleration due to gravity and then slid horizontally with constant deceleration.

(a) How long did the mud take to drop the 460 m?

(b) How fast was it traveling when it reached the bottom?