Here is your answer
[tex] \huge\frac{ - 5}{21} [/tex]
REASON:
Given,
[tex] \frac{ - 1}{7} \times \frac{5}{3} [/tex]
The numerator of one fraction is multiplied to the numerator of other and same is in the case of denominator.
[tex] \frac{ - 1 \times 5}{7 \times 3} [/tex]
[tex] = \frac{ - 5}{21} [/tex]
HOPE IT IS USEFUL