It says that there was an error with my answer, but I don't know what, so I screenshotted what I typed and attached them as 4 images below:
A because the origin is at 0,0 and point A is at 0,0
Given:
Schaum's earnings in a month = 
His wife's earnings in a month = 
Where x is the number of working days in a month.
To find:
The total earnings in a month.
Solution:
We know that,
Total earnings = Schaum earnings + His wife's earnings in a month



Therefore, the correct option is A.