Q:

How to solve for $n$?

e.g.
$$\int_1^n \frac{1}{x} dx = \pi$$
I want to know the method used to solve it for any constant $c$ of any integral.

A:

We have $\int_1^n \frac{1}{x} dx = \ln (n) = \pi$ therefore $e^{\ln n} = e^{\pi} = n.$

