Each of the puzzles below is actually 3 puzzles in 1.  First black out 2 of the squares so that the remaining equation is true.  Then black out 3 different squares to make a correct equation.  Then do it with 4 squares.  The standard order of operations is used: multiplication and division are done before addition and subtraction.  Only whole numbers are used, though the results might be negative.  A sample puzzle is shown below. 
 
Each puzzle below has a unique solution.  →
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