We in are learning to find a lot of ways to find out problems in our maths classes and this is one of them. The strategy that I have used is called Equal Additions. Watch and try to follow on how I explain what to do when these sort of equations.
Explanation: What I did first was I added 2 on each number so that the problem becomes much easier in this case 180-80 instead of the complicated way 182-78. This strategy is called equal additions and can only be used with subtraction .
Always and the same amount on both numbers.
Try to make the equation a question that you find easy.