Final answer:
Cynthia can deduct 90 miles from her taxable income for business-related travel.
Step-by-step explanation:
To calculate the distance that can be deducted, we need to determine the total distance traveled by Cynthia. We can split her journey into three parts:
- From home to Blue Corporation: 30 miles
- From Blue Corporation to Wren Corporation: 20 miles
- From Wren Corporation to home: 40 miles
Adding up these distances gives us a total of 30 + 20 + 40 = 90 miles. Therefore, Cynthia can deduct 90 miles from her taxable income for business-related travel.