HELP PLZ
Courtney stands at the top of a cliff and drops a rock. The height of the rock, in feet, is given by the function f(x)=-16x^2+23, where x is the number of seconds after she releases the rock.
At the same moment, Courtney releases her rock, her brother Dayton, who is on the ground under and several meters to the left of Courtney, throws a rock straight up in the air. The height of his rock, in feet, is given by the function f(x)=-16x^2+30x, where x is the number of seconds after he releases the rock.
When are the rocks at the same height? Round to the nearest hundredth of a second.

Question

HELP PLZ
Courtney stands at the top of a cliff and drops a rock. The height of the rock, in feet, is given by the function f(x)=-16x^2+23, where x is the number of seconds after she releases the rock. 
At the same moment, Courtney releases her rock, her brother Dayton, who is on the ground under and several meters to the left of Courtney, throws a rock straight up in the air. The height of his rock, in feet, is given by the function f(x)=-16x^2+30x, where x is the number of seconds after he releases the rock.
When are the rocks at the same height? Round to the nearest hundredth of a second.