M: Mike's stickers
D: Dan's stickers
Mike has 4 times as many stickers as Dan:
M = 4D
They will each have 150 stickers, so they will have a total of 300 stickers:
M + D = 300
Replacing M, from the first equation into the second equation:
4D + D = 300
5D = 300
D = 300 / 5
D = 60
Replacing D, into the first equation:
M = 4D
M = 4 (60)
M = 240
Dan should have 150 stickers, and he already have 60, so:
150 - 60 = 90. Dan needs 90 stickers more.
Mike has 240 stickers, and he should only have 150, so:
240 - 150 = 90. Mike must give 90 stickers to Dan.
Mike must give 90 stickers to Dan, so they each have 90.
