If $$\frac{1}{y} - \frac{1}{x} = 7$$, then evaluate $$\left(\frac{11x + 5xy - 11y}{5x - 33xy - 5y}\right)\left(\frac{35x + 26xy - 35y}{3x - 20xy - 3y}\right)$$.

From $$\frac{1}{y} - \frac{1}{x} = 7$$ we get $$\frac{x - y}{xy} = 7$$, so $$x - y = 7xy$$. Grouping each numerator and denominator in terms of $$x - y$$, the expression becomes $$\frac{11(x - y) + 5xy}{5(x - y) - 33xy} \times \frac{35(x - y) + 26xy}{3(x - y) - 20xy}$$. Substituting $$x - y = 7xy$$ gives $$\frac{77xy + 5xy}{35xy - 33xy} \times \frac{245xy + 26xy}{21xy - 20xy} = \frac{82}{2} \times 271$$. Hence the value is $$41 \times 271 = 11111$$.