Final answer:
For an input of $90, the algorithm will output "Save more." because the amount is less than the $100 threshold set by the algorithm.
Step-by-step explanation:
The algorithm presented in the question checks if the amount in your bank account is greater than or equal to $100. If it is, the algorithm outputs "Yes!". If not, it outputs "Save more." Since the input is $90, which is less than $100, the expected output of this algorithm would be "Save more."