Divide the left side of the equation by 5 to isolate a on the other side. Dividing by a fraction is the same thing as multiplying by the reciprocal of that fraction. 5 is not a fraction, but we can write it as \(\frac{5}{1}\), the reciprocal of which is \(\frac{1}{5}\). So your problem can be written as \(a = \frac{1}{5}(\frac{5^{3x}·25^{x}}{5^{x-1}})\)
