[tex]( \sqrt{486} - \sqrt{294} ) \div \sqrt{3} - ( \sqrt{126} - \sqrt{350} ) \div \sqrt{7} \\ (9 \sqrt{6} - 7 \sqrt{6} ) \div \sqrt{3} - (3 \sqrt{14} - 5 \sqrt{14} ) \div \sqrt{7} \\ 2 \sqrt{6} \div 3 + 2 \sqrt{14} \div \sqrt {7} \\ 2 \sqrt{2} + 2 \sqrt{2} \\ 4 \sqrt{2} [/tex]