The equation of a line with slope m and passing through the point (x1, y1) is given by
y−y1=m×(x−x1)
Now on line AB we already know the point (x1, y1) = (3,5)
To find slope we can use the property of paralllel lines that is Slope of parallel lines are always the same i.e.
Slope of AB = Slope of PQ
Slope of a line = (y2−y1x2−x1)
Let, x1=1,x2=2y1=3, y2=5
Slope of PQ = slope of AB = (5−32−1)
= 2
So equation of line AB = y−5=2×(x−3)
= y−5=2x−6
= y−2x+1=0