To represent the inequality, let us define some variables first: 
lets say 'w' represents the greatest number of weekly withdrawals: 
Elise has budget of $800 in her checking account: 
If she withdraws $50 each week then in 'w' number of weeks she has withdrawn 
 dollars. 
The amount left in her checking account is given by: 

Now, she needs to have at least $200 available at the end of summer. 
Which means: 

The inequality 
 can be used to determine the greatest number of weekly withdrawals.