AP EAMCET Engineering 2018 Apr 22 Shift 2 Paper

If one vertex at each line then number of triangles are,
n1=5C1×7C1×9C1
n1=315
If two vertex at line L1 and remaining ether at L2 and L3 , then number of triangles are,
n2=5C2×16C1
n2=160
If two vertex at line L2 and remaining ether at L1 and L3 , then number of triangles are,
n3=7C2×14C1
n3=294
If two vertex at line L3 and remaining ether at L1 and L2 , then number of triangles are,
n4=9C2×12C1
n4=432