Step-by-step explanation:
[tex] (\frac{8.4.2}{8.7} )^{2} \times (\frac{ {8}^{0} }{{7}^{ - 3} } )^{3 } \times {7}^{ - 9} \\ \\ = (\frac{8}{7} )^{2} \times (\frac{ 1}{{7}^{ - 3} } )^{3 } \times {7}^{ - 9}..... (\because a^0=1)\\ \\ = \frac{64}{49} \times ({{7}^{ 3} } )^{3 } \times {7}^{ - 9} \\ \\ = \frac{64}{49} \times {{7}^{ 3 \times 3} } \times {7}^{ - 9} \\ \\ = \frac{64}{49} \times {{7}^{ 9} } \times {7}^{ - 9} \\ \\ = \frac{64}{49} \times {{7}^{ 9 - 9} } \\ \\ =\frac{64}{49} \times {{7}^{ 0} } \\ \\ =\frac{64}{49} \times 1 \\ \\ = \frac{64}{49} [/tex]
Thus, first option is the correct answer.
