Answer:
2) S(Δt)=So+g(Δt)
Explanation:
I think the equation they gave you for the Height upon time in seconds it's (1), where if you see, you will find the gravity, that you should multiply by 2 because, its divided by two in (1) (that should be your (a)), then, once you find your gravity, you can use the equation (2) to know the Final Speed replacing g , at the time asked, remember that g is gravity, and Δt is the: final time- initial time.
so in the [1,2] interval of time, your Δt=1s, and in [1,1.5] is Δt=0,5s.
i hoped it helped you even though i cant give you the exact answer right now.