So I am going to assume this is a logic problem.
15(2.718282

) + 7 = 10
Subtract 7 from both sides.
15(2.718282

) = 3
Divide both sides by 15.

2.718282

=

Now you solve for the exponent.
<span>(Take log of both sides)
</span>
<span><span>(<span><span>−<span>3x</span></span>+1</span>)</span>*<span>(<span>log<span>(2.718282)</span></span>)</span></span>=<span>log(1/5)
</span>
<span><span>−<span>3x</span></span>+1 = </span>

<span><span>−<span>3x</span></span>+1</span>=<span>−<span>1.609438
</span></span>
<span><span><span><span>−<span>3x</span></span>+1</span>−1</span>=<span><span>−1.609438</span>−1</span></span><span>(Subtract 1 from both sides)
</span>
<span>−<span>3x</span></span>=<span>−<span>2.609438 (divide 3 on both sides)
</span></span>
Answer:
x = <span>
0.869813
</span>
or...
Rounded Answer:
0.87