[tex]a. \: - 13 - 8 \times {2}^{2} = - 13 - 8 \times 4 = - 13 - 32 = - 45 \\ b. \: \frac{6 \times 3}{2} \div 7 = \frac{18}{2} \div 7 = 9 \div 7 \approx 1.28571[/tex]
