Find the gradient and y-intercept of the equation 2x + y = 3.

Subtract $2x$ from both sides of the equation:

Comparing $y = -2x + 3$ with $y = mx + c$, the coefficient of $x$ is the gradient.
The gradient $m = -2$.

Comparing $y = -2x + 3$ with $y = mx + c$, the constant term is the y-intercept.
The y-intercept $c = 3$.

The gradient is $\boxed{-2}$ and the y-intercept is $\boxed{3}$.