So, you first need to convert both sides to where the variable is a normal number.
Since 5 is the number that has an exponent of a variable, use that number as a base number logging both sides.
[tex]5^{c}[/tex] = [tex]250[/tex]
[tex]log_{5}[/tex][tex]5^{c}[/tex] = [tex]log_{5}[/tex][tex]250[/tex]
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c = [tex]log_{5}[/tex][tex]250[/tex]
The equation above is your answer.
