Answer:
[tex]\large\boxed{x=-\dfrac{1}{5}}[/tex]
Step-by-step explanation:
[tex]\dfrac{a-x}{x-a}=5x\\\\\dfrac{(a-x)}{-(a-x)}=5x\qquad\text{cancel}\ (a-x)\\\\-1=5x\qquad\text{divide both sides by 5}\\\\-\dfrac{1}{5}=\dfrac{5x}{5}\to\boxed{x=-\dfrac{1}{5}}[/tex]
