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 [tex]\frac{5}{1}[/tex], the reciprocal of which is [tex]\frac{1}{5}[/tex]. So your problem can be written as [tex]a = \frac{1}{5}(\frac{5^{3x}·25^{x}}{5^{x-1}})[/tex]
