Hi.

for the first condition

x = a₁t²/2

d₁-x=a₁t²+a₂t²/2

d₁=3a₁t²+a₂t²/2

similarly for the second condition

d2=3a₂t²+a₁t²/2

d1/d2=a₂+3a₁/a₁+3a₂

(since you have not given the options I have stopped here, you can get the answer in the desired form using the result derived above. If you still have trouble nudge me!)