Original formula = (-5a 2b 2)/ab.

=-5ab。

=-5* 10*(- 1/25).

=50/25.

=2.

(2) The original formula = x (x2-x)/(x2-x)-(1-x) (1+x)/(x+1).

=x-( 1-x)。

=2x- 1。

=2*2- 1.

=3.

(3) The original formula = (2a+6)/(a-2) 2 * [(a-2)/(a2+3a-1)] * (a-2).

=[(2a+6)*(a-2)^2/(a-2)^2]/(a^2+3a- 1).

= (2a+6)/(a 2+3a- 1), where a= 1/3.

=[2*( 1/3)+6]/[(( 1/3)^2+3*( 1/3)- 1].

=(20/3)*9.

=60.

(4) The original formula = [x2/(2x-x)] * [(x-1)/x]-(x2-9)/(x-3).

=[(x^2/x)*(x- 1)/x]-(x+3)(x-3)/(x-3).

=[x*(x- 1)/x]-(x+3)。

=x- 1-(x+3)。

=-4.