1. **State the problem:** We need to find the value of $x$ given the equation $\log_e 2 \cdot \log_x 625 = \log_{10} 16 \cdot \log_2 10$.
2. **Rewrite the logarithms in a common base:** Recall that $\log_a b = \frac{\log_c b}{\log_c a}$ for any positive base $c \neq 1$.
3. Express each logarithm in terms of natural logarithm $\ln$ (log base $e$):
$$\log_e 2 = \ln 2$$
$$\log_x 625 = \frac{\ln 625}{\ln x}$$
$$\log_{10} 16 = \frac{\ln 16}{\ln 10}$$
$$\log_2 10 = \frac{\ln 10}{\ln 2}$$
4. Substitute these into the equation:
$$\ln 2 \cdot \frac{\ln 625}{\ln x} = \frac{\ln 16}{\ln 10} \cdot \frac{\ln 10}{\ln 2}$$
5. Simplify the right side by canceling $\ln 10$:
$$\frac{\ln 16}{\cancel{\ln 10}} \cdot \frac{\cancel{\ln 10}}{\ln 2} = \frac{\ln 16}{\ln 2}$$
6. So the equation becomes:
$$\ln 2 \cdot \frac{\ln 625}{\ln x} = \frac{\ln 16}{\ln 2}$$
7. Multiply both sides by $\ln x$:
$$\ln 2 \cdot \ln 625 = \frac{\ln 16}{\ln 2} \cdot \ln x$$
8. Divide both sides by $\frac{\ln 16}{\ln 2}$:
$$\ln x = \frac{\ln 2 \cdot \ln 625}{\frac{\ln 16}{\ln 2}} = \ln 2 \cdot \ln 625 \cdot \frac{\ln 2}{\ln 16}$$
9. Simplify the right side:
$$\ln x = \frac{(\ln 2)^2 \cdot \ln 625}{\ln 16}$$
10. Express $625$ and $16$ as powers of 5 and 2 respectively:
$$625 = 5^4 \Rightarrow \ln 625 = 4 \ln 5$$
$$16 = 2^4 \Rightarrow \ln 16 = 4 \ln 2$$
11. Substitute these back:
$$\ln x = \frac{(\ln 2)^2 \cdot 4 \ln 5}{4 \ln 2}$$
12. Cancel 4 and one $\ln 2$:
$$\ln x = \cancel{4} \cdot (\ln 2)^2 \cdot \ln 5 / (\cancel{4} \cdot \ln 2) = \ln 2 \cdot \ln 5$$
13. So:
$$\ln x = \ln 2 \cdot \ln 5$$
14. To find $x$, exponentiate both sides with base $e$:
$$x = e^{\ln 2 \cdot \ln 5}$$
**Final answer:**
$$\boxed{x = e^{\ln 2 \cdot \ln 5}}$$
Logarithm Equation A4Fc80
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