5 points are marked on a straight line and another 6 points are marked on a second straight line with no points in common. How many triangles can be constructed with vertices from among the above points?
Choose the correct choice from the following
A) 21
B) 91
C) 135
D) 196
E) 364
Solution: select 2 from 5 and one from 6 + select 2 from 6 and 1 from 5   61352*51351 + 51352*61351   = 135   Answer : 135
<result>C</result>
5 points are marked on a straight line and another 6 points are marked on a second straight line with no points in common. How many triangles can be constructed with vertices from among the above points?