Question 663295
Let the time required for the faster firework to reach the correct height be t.
Then the time for the slower firework is {{{t+0.5}}}
You know that the height for both is the same. You also know that the distance to that distance is given by {{{height = speed * time}}}

You are told the speed for both fireworks.
So
{{{SpeedOne * t = SpeedTwo * (t +0.5)}}}
{{{220 * t = 200(t+0.5)}}}
{{{220t = 200t + 100}}}
{{{20t = 100}}}
{{{t = 5}}}
So 5 seconds after the faster one gets fired, they will both explode at a height of 1100 feet.