X(x-a)-y(y-a) factorise this pls ..

Dear Student,

Given: x(x-a)-y(y-a)
      => x² - ax - y² - ay
      => x² - y² - a(x + y)                 | We know : x² - y² = (x + y)(x - y)
      =>(x + y)(x - y) - a(x + y)
      => (x + y)( x - y - a)

Regards