Answer:
Country A won 79 medals, country B won 29 medals and country C won 16 medals.
Explanation:
This question is solved by a system of equations.
I am going to say that:
Country A won x medals.
Country B won y medals.
Country C won z medals.
Total of 124 medals:
This means that
.
Country B won 13 more medals than Country C.
This means that

Country A won 34 more medals than the total amount won by the other two.
This means that:

From the first equation, we have that:

So






Finding z:
Since






Finding y:

Country A won 79 medals, country B won 29 medals and country C won 16 medals.