7 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? Select.
A) 91 B) 105 C) 196 D) 21 E) 231
getting the answer 231 which is not in the choices, what is the source of the problem?   7C2* 6C1 + 6C2* 7C1 =231   231
<result>E</result>
7 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?