There were w dollars in Olivia's wallet. She collected x more dollars from an atm. After she visited a supermarket there were y dollars left. How much more money did she spend at the supermarket than she collected at the atm?
First, we need to find out how much money Olivia had in her wallet after she collected money from the ATM. We know that she started with w dollars, and she collected x more dollars. This means that she had w + x dollars in her wallet after she collected money from the ATM. 

Now, we need to find out how much money she had in her wallet after she visited the supermarket. We know that she had y dollars left after she visited the supermarket. This means that she must have spent w + x - y dollars at the supermarket. 

Finally, we need to find out how much more money she spent at the supermarket than she collected at the ATM. To do this, we need to subtract the amount of money she collected at the ATM from the amount of money she spent at the supermarket. We know that she collected w + x dollars at the ATM, and she spent w + x - y dollars at the supermarket. This means that she spent w + x - (w + x - y) dollars more at the supermarket than she collected at the ATM. 

This can be simplified to: 

y - x


Therefore, the answer (symbolic expression) is: 