Answer:
146
Step-by-step explanation:
Since John works for 9 hours and makes 14 an hour. You multiply 14 by 9 which equals 126. You add 20 from the tips to 126. This makes 146.
have joint density
We can find 
by integrating the joint density over the region in 
where 
in the first quadrant, i.e. above the line 
:
using the fact that
Then using the same property,
