Réponse:
[tex] b = \frac{5 \times ( - 7) \times {10}^{2 - 3 + 2 \times 3} }{ {7}^{2} \times {10}^{5 + 1} \times 3 \times 5} = - \frac{ {10}^{5} }{7 \times {10}^{6} \times 3 } = \frac{ - 1}{21 \times {10}^{6 - 5} } = \frac{ - 1}{21 \times 10} = \frac{ - 1}{210} [/tex]
