5000=5•7^.5x

$$\\5000=5\times7^{0.5}x\\\\
5000=5\times \sqrt7\;x\\\\
1000= \sqrt7\;x\\\\
x= \frac{1000}{\sqrt7}\\\\
or\\\\
x=\frac{1000\sqrt7}{7}$$

.

5000=5*7^5x

1000=7^5x

5x=log7^1000

5x=3.549883987364815

x=0.709976797472963