Physics homework. gravity problem

A boy tosses a coin straight up to 2.8 m. Suppose the height when the coin leaves his hand is 1.4 m. What was the initial speed of the coin when it left his hand

how to do it?

use the equation of motion u*2 = v*2 + 2as

The height (s) the coin travels on its way up is 1.4m
the acceleration due to gravity (a) is (-9.8)m/s*2
the final speed of its upward journey (v) is 0m/s.

therefore, by rearranging the equation, we get u*2 = 0 - 2 x (-9.8) x 1.4
so u*2 = 27.44
so u = 5.24 m/s

how long did it take to hit the ground? other wise you cant do the problem?