How do you ignore data and calculate other data in the same cell ie 21A (5.5)

Hi there I have a cell with two parts of data which looks like this 21A (5.5) now 21A is a location plot number and the (5.5) is the area in rods of the plot.

Now I need to calculate the cost of this plot by multiplying the number of rods by the cost per rods, so is there a way of just using the number in the brackets in a sum and ignoring the rest of the information, now I know I could just make another cell with the 5.5 bit in it but it makes the spread sheet too complicated and wide

Thanks in advance

Sean