Problem C. 1270. (January 2015)
C. 1270. There are a few lines and a few circles drawn on a sheet of paper. Every two of them intersect each other, but no three pass through the same point. What are the numbers of lines and of circles if the number of intersection points is 75?
(5 pont)
Deadline expired on 10 February 2015.
Statistics:
>134 students sent a solution.  
5 points:  64 students. 
4 points:  13 students. 
3 points:  13 students. 
2 points:  17 students. 
1 point:  16 students. 
0 point:  11 students. 
