I believe the correct response is option C.
Answer:
Step-by-step breakdown:
You may consider a structure like the following while keeping in mind your specific notation.
1. | ~( (~Q ->~R) v (R & ~Q) ) Assume
2. | | ~(~Q ->~R) Assume
3. | | | ~(R & ~Q) Assume
4. | | | ~R v Q 3, De Morgan
5. | | | ~Q -> ~R 4 Material implication
6. | | | # 2, 5 Results in a contradiction
7. | | R & ~Q 3-6 indirect proof outcome
8. | ~(~Q ->~R) -> (R & ~Q ) 2-7 Discharging the conditional proof
9. | (~Q ->~R) v (R & ~Q) 8 Material implication derived
10 | # 1,9 Results in contradiction
11. (~Q ->~R) v (R & ~Q) 1-10 Completion via indirect proof
Answer: 6000 steps Step-by-step explanation: 1/15 +1/10+1/2=2/30+3/30+15/30=20/30=2/3. Therefore, 2/3 equals 12000 steps, meaning 1/3 is 6000 steps. Overall, she should tally 18000 steps, and she has recorded 12000 steps, hence 18000-12000=6000 steps.