The trick with the last one in your head is not trying to do the whole thing. The first part is relatively easy: 9.02. The answer to the second part is a number bigger than seven, so that's (a) and (b) ruled out. It's also a number that ends in one, and so the only possible answer is (d).
I remember as kids, we spent about a year being taught how to add letters together??? WTF? Never used it, never will, would have been better off learning something useful.
I don't want to brag but i got 70% right.. I found the easiest one being how much does the estate agent make, not that it's an everyday occurance, but I'm in the process of selling and buying again, gotta keep on top of it.