2100 stickers are in 3 bags.
The 2nd bag has 200 stickers more than the total number of stickers in the 3rd and 1st bags.
The 1st bag has 4 times as many stickers as the 3rd bag.
How many stickers does the 2nd bag contain?
Choose the bag with the least stickers to be 1 u.

Number of stickers in the 3rd bag = 1 u
Number of stickers in the 1st bag = 4 u

Number of stickers in the 3rd bag and 1st bag
= 1 u + 4 u
= 5 u

Number of stickers in the 2nd bag = 5 u + 200

Total number of stickers
= 1 u + 4 u + 5 u + 200
= 10 u + 200

10 u + 200 = 2100
10 u = 2100 - 200
10 u = 1900

1 u = 1900 ÷ 10 = 190

Number of stickers in the 2nd bag
= 5 u + 200
= 5 x 190 + 200
= 950 + 200
= 1150

Answer(s): 1150