Answer:
The ship will be [tex]37.5\ km[/tex] far from its port 3.5 hours from now
Step-by-step explanation:
Hi
The function is [tex]y=5x +20[/tex] relates the number of kilometers y the ship will be from its port x hours from now, it has a form [tex]y=vt+y_{0} \ where \ y\ is\ final\ distance\\v\ is\ velocity\ in\ km/h,\ t\ is\ time\\and\ y_{0}\ is\ initial\ distance[/tex].
As the function is clearly defined, we only have to evaluate it for [tex]x=3.5[/tex], so [tex]y(3.5)=5(3.5)+20=17.5+20=37.5 \ km[/tex] is the distance between the cruise ship and its port after 3.5 hours.