To go a distance of $144\text{km}$ upstream, a rower takes $12\text{hours}$ while it takes her only $9\text{hours}$ to row the same distance downstream. The speed of the stream is ______.

Let the speed of the rower in still water be $u\text{km/h}$ and the speed of the stream be $v\text{km/h}$.Upstream speed ($u-v$):
$$u-v=\frac{\text{Distance}}{\text{Upstream Time}}=\frac{144}{12}=12\text{km/h}\text{— (Equation 1)}$$
Downstream speed ($u+v$):
$$u+v=\frac{\text{Distance}}{\text{Downstream Time}}=\frac{144}{9}=16\text{km/h}\text{— (Equation 2)}$$
To find the speed of the stream ($v$), subtract Equation 1 from Equation 2:
$$(u+v)-(u-v)=16-12$$
$$2v=4$$
$$v=2\text{km/h}$$
The speed of the stream is $2\text{km/h}$.