Find the common difference. From 2020 to 2320 is 300 over 3 steps.<br><br>&bull; Common difference = 300 ÷ 3 = 100<br>&bull; First blank: 2020 + 100 = 2120<br>&bull; Second blank: 2120 + 100 = 2220<br>&bull; Check: 2220 + 100 = 2320 ✓<br>&bull; Third blank: 2420 + 100 = 2520<br><br>Final Answer: 2120, 2220, 2520