Two tracks are parallel. The first track has 6 checkpoints and the second one has 10 checkpoints. In how many ways can the 6 checkpoints of first track be joined with the 10 checkpoints of the second to form a triangle?	Choose the correct choice
A) 120  B) 150  C) 200  D) 270  E) 420
To make a triangle, you need 2 checkpoints from one track and 1 from the other. You cannot have all 3 from the same track since then the points will be in a line (assuming straight line of track)   You select 2 checkpoints from the first track and one from the second or two from the second track and one from the first.   6C2 * 10C1 + 10C2 * 6C1 = 150 + 270= 
<gadget id="calculator">150 + 270</gadget>
<output>420</output>
420   Answer (420)
<result>E</result>
Two tracks are parallel. The first track has 6 checkpoints and the second one has 10 checkpoints. In how many ways can the 6 checkpoints of first track be joined with the 10 checkpoints of the second to form a triangle?