Express $\mathrm{y}$ as a function of $\mathrm{x}$. The constant $\mathrm{C}$ is a positive number. \[ \ln y=\ln 20 x+\ln C \]

Step 1 ：Given the equation in logarithmic form: \(\ln y=\ln 20x+\ln C\)

Step 2 ：Using the property of logarithms that states that \(\ln(a*b) = \ln(a) + \ln(b)\), we can combine the terms on the right side of the equation: \(\ln y=\ln (20xC)\)

Step 3 ：Converting the equation into exponential form using the property that if \(\ln(a) = b\), then \(a = e^b\), we get: \(y = 20Cx\)

Step 4 ：Final Answer: The function of y in terms of x is \(\boxed{y = 20Cx}\)