Question

I am a professional base jumper and want to impress the crowd with my daring. I need to calculate the maximum amount of time I can free-fall before opening my parachute, and still land safely. Assume that the parachute will take 1.0 second to open after I pull the cord, during which time I continue to accelerate downwards at -9.8 m/s^2. After the parachute opens, it will slow me down steadily by +4 m/s^2. A safe landing speed in the New River is 12 m/s^2. What is the maximum time I can free fall before pulling the rip cord?