Step 1: Identify the highest derivative.
The given equation involves the first derivative \( \frac{dy}{dx} \) and the second derivative \( \frac{d^2y}{dx^2} \). The highest derivative present is \( \frac{d^2y}{dx^2} \).
Step 2: Determine the order.
The order of a differential equation is determined by the highest order of the derivative of \( y \). In this case, the highest order is 2 because \( \frac{d^2y}{dx^2} \) is the highest derivative.
Final Answer: \[ \boxed{2} \]
Let \( y = y(x) \) be the solution of the differential equation \[ \frac{dy}{dx} + 2y \sec^2 x = 2 \sec^2 x + 3 \tan x \cdot \sec^2 x \] such that \( y(0) = \frac{5}{4} \). Then \[ 12 \left( y\left( \frac{\pi}{4} \right) - e^{-2} \right) \] is equal to _____.