The point $P(a, b)$ lies on the straight line $3 x+2 y=13$ and the point $Q(b, a)$ lies on the straight line…
The point $P(a, b)$ lies on the straight line $3 x+2 y=13$ and the point $Q(b, a)$ lies on the straight line $4 x-y=5$. Then the equation of the line $P Q$ is