please explain how to do this. tried to solve but cant do it

Answer:
2.55km
Step-by-step explanation:
[tex]d=st[/tex]
where:
d=distance
s=speed
t=time
[tex]s=\frac{3.4 \ \text{km}}{\text{hr}}\\[/tex]
[tex]t=0.75 \text{hr}[/tex]
[tex]d=st=(\frac{3.4 \text{km}}{\text{hr}})(0.75 \text{hr}})=2.55 \text{km}\\[/tex]
Answer:
[tex]3\frac{2}{5}[/tex] × [tex]\frac{3}{4}[/tex] [tex]= 2\frac{11}{20}[/tex] km
= 2.55 km