An elevator with a mass 1000kg accelerates downward at 3m/s^2. What is the maximum tension the cable can support if it's breaking strength is 15000N? What is the maximum upward acceleration?

I got the maximum tension by doing.
T = (1000kg)(9.8m/s^2)-(1000kg)(3m/s^2) = 6800N

But I cannot get maximum upward acceleration...The answer says it should be 6