This is a logical statement, of the form
[tex]\urcorner(p\lor q)[/tex]where p is the statement "the test is today" and q is the statement "the party is tonight". The DeMorgan's Law indicates that:
[tex]\urcorner(p\lor q)\equiv\urcorner p\wedge\urcorner q[/tex]Therefore the equivalent statement is " the test is not today and the party is not tonight".