To write the equation of a line in slope-intercept form \( y = mx + b \), where \( m \) is the slope and \( b \) is the y-intercept, we can start with the given slope and a point on the line.
The slope \( m \) is given as \( -1 \), and the point through which the line passes is \( (-5, 3) \).
We can use the point-slope form of the equation of a line, which is given by:
\[ y - y_1 = m(x - x_1) \]
Here, \( (x_1, y_1) \) is the point \((-5, 3)\). Substituting the values into the point-slope form:
\[ y - 3 = -1(x + 5) \]
Next, we'll simplify this equation step-by-step:
- Distribute the slope on the right side:
\[ y - 3 = -x - 5 \]
- Add 3 to both sides to isolate \( y \):
\[ y = -x - 5 + 3 \]
- Combine like terms:
\[ y = -x - 2 \]
Now, we have the equation of the line in slope-intercept form:
\[ \boxed{y = -x - 2} \]