Answer:
1. 24
2. 
 where n denotes number of days.
3. 70
Explanation:
1.
Consider the sequence: 

Here,

Take the common difference as d = 2 and the first term as a = 12
Use the formula: 

To find expected gain at the end of the week, find 


2. 
Yes, the gain shows the pattern.
Put 
 in 


Here, n denotes number of days.
3.
To find expected gain at the end of 30 days, put 
 in 

