[tex]15 \sqrt{14} \div (3 \sqrt{28} - \sqrt{63} ) + 2 \sqrt{10} \times ( \sqrt{80} - 2 \sqrt{45} ) = 15 \sqrt{14} \div (6 \sqrt{7} - 3 \sqrt{7} ) + 2 \sqrt{10} \times (4 \sqrt{5} - 6 \sqrt{5} ) = 15 \sqrt{14} \div (3 \sqrt{7} ) + 2 \sqrt{10} \times ( - 2 \sqrt{5} ) = 5 \sqrt{2} - 4 \sqrt{50} = 5 \sqrt{2} - 20 \sqrt{2} = - 15 \sqrt{2} [/tex]