a rocket propeled sled moved along a track at 1020km/h He and the sled were brought to a stop in 1.4s In g units what acceleration did he e xperiance while stopping?

I know 1 g = 9.8m/s^2
I used a=(v-v0)/t and got 74.344 g
Is this correct?

Acceleration, or in this case deceleration, is (v_f - v_0)/time
v_0=1020km/h, v_f=0, t=1.4sec
Are you sure it's 1020km/hr? That seems a bit high.
1020km/hr=1,020,000m/3600sec=283.3m/sec
So a=-283.3m/sec/1.4sec=approx 202m/sec^2
202/9.8=approx 20.7g
Check my arithmetic. I'm not sure how you got your answer.