She forgot to distribute the 2 fully.
ie. After the 3 to the 9x.
It should have been,
2(3 + 9x) - 2x
6 + 18x - 2x
6 + 16x
a. The events are mutually exclusive, so
b. For the same reason,
Another way to see this is to use the result from part (a), and the inclusion/exclusion principle:
and the right side reduces to 0.
c. Same as (b),
d. Same as (b),
We can also use the distributivity rule for unions and intersections to write
e. If the 
is the complement of 
, then by DeMorgan's law,
Answer:
8.5
Step-by-step explanation:
It will form a triangle with perpendicular=3km and base=8km. The distance is sqrt((3)^2+8^2)=9+64=sqrt(73)=8.5
Answer: 8 hours
Step-by-step explanation: You would first multiply 2 hours by 4 mph, and get 8 miles. You would then subtract 8 miles from 26 miles, and have 18 miles left. You would now divide 18 miles by 3, as he is now traveling 3 miles per hour and needs to travel 18 miles. You would get 6 hours. You would now add 6 hours by the 2 hours initially traveled at 4 mph, and get 8 hours.
