Shae is covering 3 walls in her bedroom with wallpaper. The measurement of each wall is 12ft x14 ft a roll of wallpaper covers 42 square feet. How many rolls should Shae purchase

1 wall is 12x14 so that's 168 square feet

it's 3 walls so 3x168 is 504

each thing of wallpaper covers 42 square feet so divide 504 by 42 (and if you have a fraction/remainder, round up)

504/42 is 12 though so you don't need to round, the answer is just 12