## Prealgebra (7th Edition)

$area=180\ ft\times175\ ft=31500\ sqft$ $\frac{1\ bag}{4000\ sqft}=\frac{x\ bag}{31500 \ sqft}$ Use cross multiplication to solve for x. $4000x=1\times31500$ $4000x\div4000=31500\div4000$ $x=7.875$