A distant galaxy is determined to be 150 million light years distant and moving away from us; using the Hubble law determine its velocity in terms

Your question kind of petered out there towards the end and you didn't specify

the terms, so I'll pick my own.

The "Hubble Constant" hasn't yet been pinned down precisely, so let's pick a

round number that's in the neighborhood of the last 20 years of measurements:

70 km per second per megaparsec.

We'll also need to know that 1 parsec = about 3.262 light years.

So the speed of your receding galaxy is

(Distance in LY) x (1 megaparsec / 3,262,000 LY) x (70 km/sec-mpsc) =

(150 million) x (1 / 3,262,000) x (70 km/sec) =

3,219 km/sec in the direction away from us (rounded)