Let's say Janet had x dollars in her account.
After Monday, when she deducted 5 dollars, she has x - 5 dollars left.
After Tuesday, when she deducted 6 dollars, she has x - 5 - 6 = x - 11 dollars left.
So, the expression would be:
x - 11
In total, Janet deducted 11 dollars from her account because 5 + 6 = 11.