皮特（Peter）有一些贴纸。他把其中的一半加额外的60张贴纸送给了塞缪尔（Samuel）。接着，他把剩下贴纸的一半加额外的30张送给了特洛伊（Troy）。然后，他给他的3个兄弟姐妹每人送了40张贴纸，最后还剩100张。皮特最初有多少张贴纸？ 答案：___

1. Calculate the number of stickers Peter had before giving to his 3 siblings.

Stickers given to siblings = $3 \times 40 = 120$
Stickers before giving to siblings = $100 + 120 = 220$

2. Work backwards to find the remainder after giving stickers to Samuel.

Before giving to Troy, Peter gave half of the remainder and an additional 30 stickers. So the amount before giving to Troy (which is the remainder after Samuel) is:
$\text{Half of remainder} = 220 + 30 = 250$
$\text{Remainder after Samuel} = 250 \times 2 = 500$

3. Work backwards to find the initial number of stickers.

Before giving to Samuel, Peter gave half of his initial stickers and an additional 60 stickers. So the initial amount is:
$\text{Half of initial} = 500 + 60 = 560$
$\text{Initial amount} = 560 \times 2 = 1120$