Danny collects bottle caps and wrappers. He found w wrappers and x bottle caps at the park. Now he has y bottle caps and z wrappers in his collection. How many more bottle caps than wrappers did danny find at the park?
Danny found w wrappers and x bottle caps at the park. 

This means that the number of bottle caps he found, x, is w more than the number of wrappers he found, w. 

Now he has y bottle caps and z wrappers in his collection. 

This means that the number of bottle caps he has in his collection, y, is z more than the number of wrappers he has in his collection, z. 

Now we need to compare x to y and w to z. 

x is w more than y and w is z more than z. 

This means that x is z more than y. 

Therefore, Danny found z more bottle caps than wrappers at the park.