If 5cm on a map represent 4.5km. What is the scale of the map in representative fraction

Explanation:

Representative fraction is simply ratio so if 5 cm represents 4.5km we will have to convert it to centimeters which is:

5:4.5*10000

5:450000

in the lowest term that will be

1:90000

1:90,000 is the answer

answer at the divergent plate boundary in the middle of the ocean;