Lauren bought 15 rainbow and balloon stickers for her little sister. The rainbow stickers cost 3 cents apiece and the balloon stickers cost 6 cents apiece. If Lauren spent exactly 81 cents, how many of each type of sticker did she buy?

3 rainbow stickers and 12 balloon stickers

Step-by-step explanation:

Let x = rainbow count

Let y = balloon count

x + y = 15

x = 15 - y

        3x + 6y = 81

3(15 - y) + 6y = 81

45 - 3y + 6y = 81

                3y = 36

                  y = 12

x = 15 - 12

x = 3