Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
Bert, Ernie, and Peggy collect stamps.  Bert has four times as many stamps as Ernie, but Ernie has three times as many stamps as Peggy.  If Peggy currently has 75 stamps in her collection, how many stamps does she need to add to her collection to have a collection as large as Bert's collection?

### Response:
If Peggy has 75 stamps, and Ernie has three times as many stamps as Peggy, then Ernie has 3*75 = <<75*3=225>>225 stamps.
Since Bert has four times as many stamps as Ernie, then Bert has 4*225 = <<4*225=900>>900 stamps.
Therefore, Peggy needs 900-75= <<900-75=825>>825 more stamps to have a collection as large as Bert's.
#### 825