For 8 innings, Miraz has an average of 60 runs. In the 9th inning, he scored 6 runs, thus decrease his average. How much does his average decrease?

Question: For 8 innings, Miraz has an average of 60 runs. In the 9th inning, he scored 6 runs, thus decrease his average. How much does his average decrease?

Solution:
Total score for 8 innings = 60 × 8 = 480
Total score after 9th innings = 480 + 6 = 486

∴ the new average is = 486/9 = 54

So, his average decrease = 60 - 54 = 6