2200 stickers are in 3 packets.
The 3rd packet has 100 stickers more than the total number of stickers in the 2nd and 1st packets.
The 1st packet has 2 times as many stickers as the 2nd packet.
How many stickers does the 3rd packet contain?
Choose the packet with the least stickers to be 1 u.

Number of stickers in the 2nd packet = 1 u
Number of stickers in the 1st packet = 2 u

Number of stickers in the 2nd packet and 1st packet
= 1 u + 2 u
= 3 u

Number of stickers in the 3rd packet = 3 u + 100

Total number of stickers
= 1 u + 2 u + 3 u + 100
= 6 u + 100

6 u + 100 = 2200
6 u = 2200 - 100
6 u = 2100

1 u = 2100 ÷ 6 = 350

Number of stickers in the 3rd packet
= 3 u + 100
= 3 x 350 + 100
= 1050 + 100
= 1150

Answer(s): 1150