Answer:
D. 10
Step-by-step explanation:
If he hits 8 swings every 24 swings, that gives you a ratio of 1 hit:3 swings. Using this ratio, you can take the 8 hits he already has, and add them on the 6 extra swings he did to get 30 swings. Using the ratio, he hits 2 more, and 8+2=10, so D.