Hello i have an aptitude test soon for Nissan and i know for a fact it's basically find out what the missing number is in the equations e.g 5 x 5 - ? + 10 = 30. I need to work out what the Question Mark is in each Equation and only get 16-20 seconds to do them. There is a method for working them out depending on where the question mark is in the equation. If it's on the left you just swap all the symbols such is - becomes + ect ect. Also what are these type of equations called because ive been trying to find them on the net to do some tests on them to get a bit of practice but can't find any. I was told they're called Timed Inversions but after looking on the net i'm unable to find anything relating to what I'm looking for.