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It is the most stupid instruction to write a system of three equation,
which can accompany this problem.
Normally , it is solved using only ONE unknown and ONE equation.
Since there were 24 individuals placed, and since there were as many first-place finishers as second-place and third-place
finishers combined, it implies that there were 12 first-place finishers and 12 second-place and third-place finishers combined.
Let x be the number of the second-place finishers; then the number of the third-place finishers is (12-x).
So we have one unknown x and the equation for the total points in the form
3*12 + 2x + 1*(12-x) = 53.
Simplify and find x
36 + 2x + 12 - x = 53
2x - x = 53 - 36 - 12
x = 5.
ANSWER. There were 12 first-place finishers, 5 second-place finishers and (12-5) = 7 third-place finishers.
Solved.