1. If a is an odd number and b is an even number, then which of the following must be an even number ?   2a + b   ab + 1   a + b + 2   a + b   2b + a   Hint Half-n-half Clue   2. If f(x, y) = 2 y - x2 where x and y are real numbers, then f( f(4, 7), 7) is equal to   -18   10   -2   2   -10   Half-n-half Clue   3. If a and b are both odd numbers, then which of the following must be an odd number ?   a + b + 2   a + b   ab   2a + b + 1   ab + 1   Half-n-half Clue   4. Last month, Mr. Anderson spent 5% of his salary to pay his electricity bill, 12% to pay his phone bill, and 63% for general monthly expenses. If his salary is $ 3100, then his savings last month was   $ 155   $ 372   $ 620   $ 2480   $ 1953   Half-n-half Clue