Uncertenties follow the form: $x\pm\Delta x\text{ unit}$
Examples: ✅ $53\pm2 \text{ cm}$ ; $(3.45\pm 0.12)10^{-9} \text{ g}$ ❌ $49\pm3.2 \text{ W}$ ; $4.010^2\pm50 \text{ AU}$
$$ (\Delta y)^2=(\Delta A)^2+(\Delta B)^2 $$
$$ \left(\frac{\Delta y}{y}\right)^2=\left(\frac{\Delta A}{A}\right)^2+\left(\frac{\Delta B}{B}\right)^2 $$
$$ \Delta A=\Delta x $$
$$ \frac{\Delta A}{A}=\frac{\Delta x}{x} $$
$$ \frac{\Delta A}{A}=|n|\frac{\Delta x}{x} $$
$$ \frac{\Delta A}{A}=\Delta x $$
$$ \left(\sigma_A\right)^2 = \left(\sigma_x\right)^2 + \left(\sigma_y\right)^2
$$ \left(\frac{\sigma_A}{A}\right)^2 = \left(\frac{\sigma_x}{x}\right)^2 + n^2 \left(\frac{\sigma_y}{y}\right)^2