During liftoff a hot-air balloon accelerates upward at a

Question

Problem: During liftoff, a hot-air balloon accelerates upward at a rate of 3.5m/s². The balloonist drops an object over the side of the gondola when the speed is 15m/s.

Part A: What is the magnitude of the object's acceleration after it is released (relative to the ground)?

Please show steps to find the magnitude of the object's acceleration after it is released.