Lines & Planes in Space · Medium problem

A probe starts at the point $(2,1,0)$, which lies on the plane $3x+4y=10$ (check: $3(2)+4(1)=10$). It flies at a constant speed of $3$ m/s straight along the direction perpendicular to this plane, toward the parallel plane $3x+4y=55$. After how many seconds does the probe reach the second plane?