1 | initial version |

You have two definitions (with the `=`

sign) of `p_ges`

. One of them is the symbol

```
p_ges = var('p_ges', latex_name=r'\varphi_{ges}')
```

and the other one is the right-hand side of some equation `p_ges == p_1 + p_2 + p_3 + p_4`

.

You should probably give this right-hand side a different name, e.g.

```
p_ges_rhs = p_1 + p_2 + p_3 + p_4
```

Then the equation you want to solve is

```
d = solve(p_ges == p_ges_rhs, d_k)
```

2 | No.2 Revision |

You have two definitions (with the `=`

sign) of `p_ges`

. One of them is the symbol

```
p_ges = var('p_ges', latex_name=r'\varphi_{ges}')
```

and the other one is the right-hand side of some equation `p_ges == p_1 + p_2 + p_3 + p_4`

.

You should probably give this right-hand side a different name, e.g.

```
p_ges_rhs = p_1 + p_2 + p_3 + p_4
```

Then the equation you want to solve is

```
d = solve(p_ges == p_ges_rhs, d_k)
```

Your old line 47 is equivalent to

```
d = solve(p_ges_rhs == 0, d_k)
```

which explains why `p_ges`

doesn't appear (it is implicitly set to zero).

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