Can someone please help me solve this....D=

A stone is thrown straight down from the edge of a roof, 725 ft above the ground, at a speed of 7 ft/sec.

A. Given that the acceleration due to gravity is -32 ft/sec2, how high is the stone 4 seconds later? ft.

B. At what time does the stone hit the ground? sec.

C. What is the velocity of the stone when it hits the ground? ft/sec.

For A. I got -10 and for B. I got -7sqrt(7^2-4(-16)(725)) but those answers were wrong and I don't know how to do C. Pleasee help!

Question

Can someone please help me solve this....D=

A stone is thrown straight down from the edge of a roof, 725 ft above the ground, at a speed of 7 ft/sec.

A. Given that the acceleration due to gravity is -32 ft/sec2, how high is the stone 4 seconds later?   ft.

B. At what time does the stone hit the ground?   sec.

C. What is the velocity of the stone when it hits the ground?   ft/sec.

For A. I got -10 and for B. I got -7sqrt(7^2-4(-16)(725)) but those answers were wrong and I don't know how to do C. Pleasee help!