Answer :
factor out the "x" and you'll have:
[tex]x(a-1) =c \qquad /:(a-1) \\ x=\frac{c}{a-1} \qquad \qquad a\neq 1 [/tex]
[tex]x(a-1) =c \qquad /:(a-1) \\ x=\frac{c}{a-1} \qquad \qquad a\neq 1 [/tex]
