\(x-y-a\left(x-y\right)\)
\(=\left(x-y\right)-a\left(x-y\right)\)
\(=\left(x-y\right)\left(1-a\right)\)
\(x-y-a\left(x-y\right)\)
\(=\left(x-y\right)-a\left(x-y\right)\)
\(=\left(1-a\right).\left(x-y\right)\)
x - y - a ( x - y )
= ( x - y ) - a ( x - y )
= ( 1 - a ) ( x - y)
x - y - a ( x - y )
= x - y - a ( x - y )
= ( x - y ) ( 1 - a )