Independent Pursuits: Puzzle

WHICH OF the following is the odd pair out:

1) EQUAL - CONTEST

2) BEAK - INVOICE

3) EXERCISE - LOCOMOTIVE

4) LARGE - FIREPLACE

5) RUBBISH - BOAT

Yesterday's answer: 43

(Any number divisible by 3, other than 3 itself, may be made up of 6s and 9s; any number >23 that leaves a remainder of 2 when divided by 3 may be made from one 20 plus 6s and 9s; any number >43 leaving a remainder 1 may be made from two 20s plus 6s and 9s.)