关于流量图中线性方程组构建正确性的确认问询

Hey everyone, I'm just starting out with linear algebra, and I'm feeling a bit unsure if I've read the flow diagram correctly. This is my first time working through a problem like this, so I don't have much confidence in the system of equations I put together.

I derived these equations from the flow diagram:

\begin{align*}
x1 + x3 - x2 = 40\\
x1 - x4 = 60\\
x3 + x4 + x5 = 10\\
x2 + x5 = 30
\end{align*}

Could someone please check if I've misinterpreted the flow directions or made any errors in setting up these equations? I'd really appreciate some clarification. Thank you!

备注：内容来源于stack exchange，提问作者dobby