Pls help question on the photo 50 points

What ratio is proportional to 18/21

Which option identifies how kevin should proceed in the following scenario? four years ago kevin designed an mp3 player for young children. now that technology has changed, he would like to update his design to ensure that it encompasses cutting-edge techniques. by creating a third-angle projection of his ideas by designing an isometric projection of his new ideas by referring to past designs and illustrations of his original model by conferring with engineers who have improved upon similar devices

Marco states that 7.696696669…… is a rational number because it is a repeating decimal. is he correct? justify your answer.