On the x y plane, there are 8 points of which 4 are collinear. How many straight lines can be formed by joining any 2 points from the 8 points ?	Options:  A) 28  B) 22  C) 20  D) 23  E) 56
Each line is defined by two points.   4 points are collinear =&gt; 1 line passes through those.   Now each of those points form 5 line =&gt; 4 lines with the "out" points and 1 line is the common one   but this is counted (the common) so we just add 4(point)*4(lines)=16 to the sum.   Finally the 4 points "out" of the common line form 4C2 = 6 different lines    1+16+6= 
<gadget id="calculator"> 1+16+6</gadget>
<output>23</output>
23 totals	ANS:23
<result>D</result>
On the x y plane, there are 8 points of which 4 are collinear. How many straight lines can be formed by joining any 2 points from the 8 points ?