Your question: Which equation can be used to find the solution of (1/3)^d−5^=81?
Just so you know: I already know someone else has answered, but I decided to give a answer that might help a bit more.. mate.
First explanation: In order to find out what "D" means, you have to create equivalent expressions in the equation that all have equal bases, then solve for d .
Second explanation: To find the solution on each answer you must move all terms not containing d to the right side of the equation.