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There are 11 points on a plane with 5 lying on one straight line and another 5 lying on other straight line which is parallel to the first line. The remaining point is not collinear with any two of the previous  points.The number of triangles that can be formed with vertices chosen from these 11 points is
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You can choose the points from the given points as follows:

2 from Line 1(L1) and 1 from Line 2(L2) = (5C2) * (5C1) = 10*5 = 50

2 from L2 and 1 from L1                       = (5C2) * (5C1) = 10*5 = 50

2 from L1 and the non collinear point     = (5C2) * (1C1) = 10

2 from L2 and the non collinear point     = (5C2) * (1C1) = 10

1 from L1, 1 from L2 and the non collinear point = (5C1) * (5C1) * (1C1) = 25

Answer= 50+50+10+10+25 = 145 Triangles
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