[tex](48.6 \div ( - 1.62) - 32.6 \div 81.5) \times ( - 2.3) = ( - 30 - 0.4) \times ( - 2.3) = - 30.4 \times ( - 2.3) = 69.92[/tex]

[tex](3 \frac{7}{9} + 3 \frac{2}{15} ) \div ( \frac{1}{20} - ( - \frac{13}{30} )) = (3 \frac{35}{45} + 3 \frac{6}{45} ) \div ( \frac{1}{20} + \frac{13}{30} ) = 6 \frac{41}{45} \div ( \frac{3}{60} + \frac{26}{60} ) = 6 \frac{41}{45} \div \frac{29}{60} = \frac{311 \times 60}{45 \times 29} = \frac{311 \times 4}{3 \times 29} = \frac{1244}{87} = 14 \frac{26}{87} [/tex]

[tex]( - 0.01x - 4.9) \times 54.2 = 0 \\ - 0.01x - 4.9 = 0 \\ - 0.01x = 4.9 \\ x = 4.9 \div ( - 0.01) \\ x = - 490[/tex]

[tex] - 8(x - 8 - 7y) = - 8x + 64 + 56y[/tex]

[tex]4 - (2x + 3y) =4 - 2x - 3y[/tex]

[tex](m + 7n - 6k) \times ( - 1.3) = - 1.3m - 9.1n + 7.8k[/tex]

[tex] - 0.8x( - 7 - 3t + 1.2p) = 5.6x + 2.4xt - 0.96xp[/tex]