## Algebra 1: Common Core (15th Edition)

$2r^{2}-5r-12$.
$A=a\cdot b$ ...the area of a rectangle. ...substitute $(2r+3)$ for $a$ and $(r-4)$ for $b$ in the formula. $A=(2r+3)(r-4)$ ...use the FOIL method. $A=(2r)(r)+(2r)(-4)+(3)(r)+(3)(-4)$ ...multiply coefficients and add exponents. $A=2r^{2}-8r+3r-12$ ...add like terms. $A=2r^{2}-5r-12$ The area of the stamp is $2r^{2}-5r-12$.