Question

How does 2:1 ratio correspond to 2/3 and 1/3?

Answer 1

"Since M and X are in a 2: 1 ratio, 2/3 of the total is M and 1/3 of the total is x."

Answer 2

Have you noticed
both 2:1 and 2/3:1/3 represent the same ratio ?

Answer 3

That's just an observation. I don't really understand your actual question

Answer 4

Suppose you and I put our own money into a bag. You put $2 and I put $1. Hence, our money is $3 and the ratio is 2:1. suppose we continue putting our money into the bag with the same ratio 2:1. At the end of the program (if there is) we need to divide the amount of total. By the ratio 2:1, your contribution is 2/3 and mine is 1/3. That is the way I understand the problem.