Multiple choice 80, 10, 70, 15, 60, ... What number should come next? 20 25 50 35 30 Reveal answer Fill a bubble to check yourself A Correct answer Explanation This is an alternating addition and subtraction series. In the first pattern, 10 is subtracted from each number to arrive at the next. In the second, 5 is added to each number to arrive at the next.