Calculate maximum ammount of Bus Bandwidth
Start from the definition.  Bandwidth is defined as data transferred per unit time.  For instance, it's the number of bytes transferred, per second.

So, work out how many bytes it would be possible to transfer across the bus, in one second.  Forget formulas: just try to reason it through.  How many 32-bit words could you transfer in one second?  How many bytes does that correspond to?