Question 1042051
<pre><b>
{{{e^(12-5x)-7=123}}}

{{{e^(12-5x)=130}}}

Learn to write exponential equations as logarithm equations:

{{{B^C=A}}} and {{{C=log(B,A)}}} are equivalent.

So {{{e^(12-5x)=130}}} is equivalent to 

{{{12-5x=log(e,(130))}}}

An abbreviation for log<sub>e</sub> is ln, so

{{{12-5x=ln(130)}}}

{{{-5x=ln(130)-12

{{{(-5x)/(-5)=ln(130)/(-5)-12/(-5)}}}

{{{x = -ln(130)/5+12/5}}}

Get your calculator:

{{{x = 1.42649311}}}

Edwin</pre>