We have,
Point P is equidistant from point A and B.
So,
Given that,P(9x,y)
A(x1,y1)=(7,0)
B(x2,y2)=(0,5)
Then, according to given,
PA=PB
√(9x−7)2+(y−0)2=√(9x−0)2+(y−5)2
On squaring both side and we get,
(9x−7)2+y2=81x2+(y−5)2
⇒81x2+49−126x+y2=81x2+y2+25−10y
⇒49−126x=25−10y
⇒10y−126x=25−49
⇒126x−10y=24
⇒2(63x−5y)=12
⇒63x−5y=6
⇒63x−5y−6=0.