a) [tex] \frac{bc-c}{ab-a}= \frac{c(b-1)}{a(b-1)}= \frac{c}{a} [/tex]
b) [tex] \frac{m-n}{m-mn} = \frac {m-n}{m(1-m)} [/tex]
c) [tex] \frac{xy+y+5x+5}{3y+15} = \frac{y(x+1)+5(x+1)}{3(y+5)} = \frac{(y+5)*(x+1)}{3(y+1)} [/tex]
d) [tex] \frac{n+n}{nx+ny+x+y}= \frac{2n}{x(n+1)+y(n+1)} = \frac{2n}{(x+y)*(n+1)} [/tex]
e) [tex] \frac{9x+9xy}{3xy+3y}= \frac{9x(1+y)}{3y(x+1)}= \frac{9}{3}[ \frac{x(1+y)}{y(x+1)}] = 3 \frac{x(1+y)}{y(x+1)}[/tex]
f) [tex] \frac{x+ax}{x+xy} = \frac{x(1+a)}{x(1+y)} = \frac{1+a}{1+y}[/tex]
