Solve for $x$ in the equation $\frac{x+1}{3} = \frac{x-1}{4}$.

1. Problem Description

Solve for $x$ in the equation $\frac{x+1}{3} = \frac{x-1}{4}$.

2. Solution Steps

To solve the equation $\frac{x+1}{3} = \frac{x-1}{4}$, we can start by cross-multiplying.

$4(x+1) = 3(x-1)$

Expand both sides of the equation:

$4x + 4 = 3x - 3$

Subtract $3x$ from both sides:

$4x - 3x + 4 = 3x - 3x - 3$

$x + 4 = -3$

Subtract $4$ from both sides:

$x + 4 - 4 = -3 - 4$

$x = -7$

3. Final Answer

$x = -7$