Let $$X\left( {{e^{j\omega }}} \right) = \sum\nolimits_{n = - \infty }^\infty {x\left[ n \right]{e^{ - j\omega n}}} $$      and $$x\left[ n \right] = \frac{1}{{2\pi }}\int\limits_{ - \pi }^\pi {X\left( {{e^{j\omega }}} \right){e^{j\omega n}}d\omega } .$$
If $$X\left( {{e^{j\omega }}} \right) = \frac{1}{{\left( {1 - 0.2{e^{ - j\omega }}} \right)\left( {1 - 0.1{e^{ - j\omega }}} \right)}},$$       what is x[n] in terms of unit discrete step function u(n)?