To find the value of $y$ when $x = 1$, substitute $x = 1$ into the equation $y = -3x + 2.5$:

$y = -3(1) + 2.5 = -3 + 2.5 = -0.5$

So, when $x = 1$, $y = -0.5$.

Would you like more details or further clarification?

Here are 5 related questions:

1. What happens to the value of $y$ as $x$ increases?
2. How would the equation change if the slope were positive?
3. What is the slope of the line represented by this equation?
4. At what value of $x$ does $y$ equal 0?
5. Can you graph this equation and identify its intercepts?

Tip: The slope of a line tells you how steep it is; in this case, a slope of -3 indicates the line is decreasing as $x$ increases.