A ball thrown horizontally from a point 24 m above the ground, strikes the ground after traveling horizontally a distance of 18 m. With what speed was it thrown?
First of all we get the time of flight from the vertical component:
The horizontal component of velocity is constant so:
see equation  and use your calculator :D
by setting the positive y-axis pointing upward and the positive x-axis pointing to the right,
at where the ball strikes,
we then isolate t,
and insert t into (1) at the striking point, assuming that y = 0
and the value of g depends on what you/your teacher uses ranging from [9,10].