Solution:
We have given that point let A(1,2) and point B(3,4) and
the equation is 3x-4y+a = 0
putting both values of A and B in LHS of equation, we get
3*1-4*2+a = 0 --------(1)
a = 5
3*3-4*4+a = 0 ------------(2)
a = 7
From both equation we get the values of a
a =5 and a= 7
So the correct answer is (b)
