Answer:
[tex]x=\frac{1}{2}at^{2}+v_{0}t\\\\1s: x=0.75(1)^{2}+3(1)=3.75m\\5s: x=0.75(5)^{2}+3(5)=33.75m\\4th=3s>>4s: x_{4} =(0.75(4)^{2}+3(4))-(0.75(3)^{2}+3(3))=8.25m[/tex]
I've written all the needed equations for you. All you have to do is some replacements.
Please do not hesitate to ask further questions.
