Question

find the value of a, for which point P ( a/3 ,2 )is the mid point of the line segment joining the point Q ( -5, 4 )and R ( -1, 0 )

Answer 1

p=(x2+x1/2 , y2+y1/2)
(a/3,2)=(-1-5/2 , 4+0/2)
by condition 
a/3=(-1-5/2)
 a/3= -3
Cross Multiplication
a=3*-3
a=-9;
Solved