1. There are 680  animals on a farm. Three-fourths of them are cows. Of the cows, about 50% are white. How many cows on the farm are not white?   170   510   340   255   255   Hint Half-n-half Clue   2. If x + y = 12 and 6 x - y = 16, then x - y is equal to   4   -4   0   -44   12   Half-n-half Clue   3. If a is an odd number and b is an even number, then which of the following must be an even number ?   ab + 1   2a + b   2b + a   a + b   a + b + 2   Half-n-half Clue   4. A gas cylinder has two vents, V1 and V2, for discharge. The cylinder empties in 6  minutes when only vent V1 is open. The cylinder empties in 5  minutes when both vent V1 and vent V2 are open. About how many minutes will the cylinder take to empty if only vent V2 is open?   cannot be determined   1.00   1.00   30.00   2.73   Half-n-half Clue