Final answer:
Melvin's mass expressed as a fraction of Kok Yang's mass is 7/2. The ratio of Kok Yang's mass to Melvin's mass is 2:7, and the ratio of Melvin's mass to the total mass of both combined is 7:9.
Step-by-step explanation:
If Kok Yang's mass is 2/7 of Melvin's mass, we need to express Melvin's mass as a fraction of Kok Yang's mass. To do this, we set Kok Yang's mass to 1 (as a convenient reference) and Melvin's mass then becomes 7/2 times Kok Yang's mass, since 1 is 2/7 of 7/2. Therefore, Melvin's mass in terms of Kok Yang's mass is 7/2.
The ratio of Kok Yang's mass to Melvin's mass, given that Kok Yang's mass is 2/7 of Melvin's mass, is simply 2:7.