There were w dollars in Olivia's wallet. She collected x more dollars from an atm. After she visited a supermarket there were x dollars left. How much more money did she collect at the atm than she spent at the supermarket?
There were w + x dollars in Olivia's wallet after she collected money from the ATM. She spent x dollars at the supermarket, so she had w dollars left. Therefore, she collected x more dollars at the ATM than she spent at the supermarket.