I have to write equations in this format:

```
    (1) A  → (*some terms*)
                   A.a = (*some terms*)
                   A.b = (*some terms*)
                   ...
                   A.z = (*some terms*)

    (2) B  → (*some terms*)
                   B.a = (*some terms*)
                   B.b = (*some terms*)
                   ...
                   B.z = (*some terms*)

    ...

    (5) E  → (*some terms*)
                   E.a = (*some terms*)
                   E.b = (*some terms*)
                   ...
                   E.z = (*some terms*)

```

The numbers ( (1), (2), etc ) have to be on the left, the '→' symbol needs to be aligned, and all the '=' symbols need to be aligned. Also, the A.a, A.b etc must start to the right of '→'.

How can I do this? I am a beginner in LateX.