Little help with Velocity and Ideal Pressure work

Ok, so I'm originally an Electrical/Electronic Engineer but as part of my current course I have to study Mechanics/Fluids, its my first year doing this type of work so I'm still pretty new to it all, I have been given a list of example questions and I'm just struggling with how I should go at them.

[COLOR=#26282a]If the water flow rate is 250 litres/second, determine the velocities at contraction inlet and exit and the ideal pressure drop (Pa) across the contraction. I am also told that at the inlet to the contraction the main has a 450mm diameter circular section which reduces to a 375mm diameter section at the contraction exit. Along with being given the Pa which is 60KPa, the water density and a kinematic viscosity of 1 x 10-6m2/s.

Above is one of the questions I was given and by looking at it I figured I had to use the continuity equation, now because I don't have A id expect that id have to use the formula A = Pi x D^2 / 4, with it saying work out the velocities I figured that I then have to work out A1 and A2 then id be able to get V1/V2, I got 0.16 for A1 and 0.11 for A2, this is where I got a little stuck because after this I know that id need to use the Flow rate which is 250 and divide it by the A values, but obviously the values are too high, so id guess that id have to convert the 250 litres/sec but I'm not 100% sure how to. With the ideal pressure drop again id guess that its the continuity equation but this time id have to use the Mass formula I just haven't fully looked at it yet.
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