arithmetic - the average temperature on monday tuesday and wednesday was 250 the average temperature on tuesday wednesday and thursday was 240 if the temperature on thursday was 270 what was the temperature on monday - skillgun

Total temperature on Monday, Tuesday and Wednesday was 250 * 3 = 750
Total temperature on Tuesday, Wednesday and Thursday was 240 * 3 = 720
Hence, difference between the temperature on Monday and Thursday = 30
If Thursday temperature = 270, then Monday's temperature = 270 + 30 = 300