3300 stickers are in 3 bags.
The 3rd bag has 400 stickers more than the total number of stickers in the 1st and 2nd bags.
The 2nd bag has 4 times as many stickers as the 1st bag.
How many stickers does the 3rd bag contain?
Choose the bag with the least stickers to be 1 u.

Number of stickers in the 1st bag = 1 u
Number of stickers in the 2nd bag = 4 u

Number of stickers in the 1st bag and 2nd bag
= 1 u + 4 u
= 5 u

Number of stickers in the 3rd bag = 5 u + 400

Total number of stickers
= 1 u + 4 u + 5 u + 400
= 10 u + 400

10 u + 400 = 3300
10 u = 3300 - 400
10 u = 2900

1 u = 2900 ÷ 10 = 290

Number of stickers in the 3rd bag
= 5 u + 400
= 5 x 290 + 400
= 1450 + 400
= 1850

Answer(s): 1850