Multiple choice general knowledge math & puzzles If 2x-y=4 then 6x-3y=? 15 12 18 20 Reveal answer Fill a bubble to check yourself B Correct answer Explanation Factor out 3 from the second expression: 6x - 3y = 3(2x - y). Since we're given that 2x - y = 4, substituting gives 3 × 4 = 12.