43) \(\frac9{5x-5y}-\frac6{7x-7y}\)

\(\frac9{5(x-y)}-\frac6{7(x-y)}=\frac{63-30}{35(x-y)}=\frac{33}{35(x-y)}\).

Ответ: \(\frac{33}{35(x-y)}\).