#### Answer

$-39$

#### Work Step by Step

$(5\sqrt{3}+6)(5\sqrt{3}-6)$
Use the FOIL method to multiply the binomial.
Multiply the First terms, the Outside terms, the Inside terms, and the Last terms.
$(5\sqrt{3}\times5\sqrt{3})+(-6\times5\sqrt3)+(6\times5\sqrt3)+(6\times(-6))$
Simplify.
$75-30\sqrt{3}+30\sqrt{3}-36$
Combine like terms/like radicals.
$-39$