what is the speed of a satellite in orbit 270km above Mercuryls surface if the mass of Mercury is 3.30x10^23kg and the radius is 2.44x10^6m?

If the satellite is in circular orbit, then the gravitation acceleration must equal the centripetal acceleration.

Let be M,R the mass and radius of Mercury, r the distance from Mercury (here 270km), and v the speed of the satellite.

Gravitation: G\frac{M}{(R+r)^2}
Centripetal: v^2/(R+r)

Then solve
G\frac{M}{(R+r)^2}=v^2/(R+r)
in v using problem's data.