SOLUTION: Given: If schools close, then workers will lose their jobs If we save fuel, then workers will not lose their jobs We save fuel or there is an energy crisis Schools will close

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since schools will close per statement 4, then workers will lose their jobs per the statement 1.
the contra-positive to statement 2 is:
if workers lose their jobs then we did not save fuel.
since we did not save fuel, then there must be an energy crisis per statement 3.