Answer:
The answer to your question is 11460 years
Explanation:
Data
Carbon-14 activity  10 cpm
half-life = 5730 yr
Real carbon-14 activity 40 cpm
Process
1.- Write a chart to solve this problem
          Real carbon-14    40 cpm    Time  0 years
          After a half-life    20 cpm     Time  5730 years
          After a half-life    10 cpm     Time 5730 years
  Total time                               11460 years     Â
2.- Conclusion
The wooden object is 11460 years old. Â Â Â Â Â Â Â Â Â Â