Set up the first prize and the second prize in the mathematics competition.
Solution: The first, second and third prizes can be regarded as "1". It is known that the first and second prizes account for 3/7 of the total number of winners, then
The number of the third prize is 1-3/7=4/7.
13/ 14 of the total number of winners who won the second and third prizes, then
The number of winners of the first prize is1-13/14 =114.