Your forehead can withstand a force of about60 kn before

Question

Problem: Your forehead can withstand a force of about6.0 kN before fracturing, while your cheekbone can only withstand about 1.3 kN.

Part A: If a 140 g baseball strikes your head at 30m/s and stops in 1.5×10³s , what is the magnitude of the ball's deceleration?

I need help to find the magnitude of the ball's deceleration.