We are asked to simplify the expression [tex] \frac{-7x}{5y} \cdot \frac{5x}{-7} [/tex],
what we do is, we form a single fraction where the numerator is the product of the numerators, and the denominator is the product of the denominators, that is:
[tex] \frac{-7x}{5y} \cdot \frac{5x}{-7}= \frac{-7\cdot5 \cdot x \cdot x}{5 \cdot(-7) \cdot y} [/tex]
simplify the common numbers and terms in the numerator and denominator:
[tex]\frac{-7\cdot5 \cdot x \cdot x}{5 \cdot(-7) \cdot y}=\frac{5 \cdot x \cdot x}{5 \cdot y}=\frac{x \cdot x}{y}= \frac{ x^{2} }{y} [/tex]
Answer: [tex]\frac{ x^{2} }{y} [/tex]