Sentences are grammatically correct and make sense.
In the first one means:
We have as much pens as they do.
Second means:
They are as tall as us.
"tan" is the equivalent in English for "as much". The concordance is well done in both cases.
Falso. No todos tienen el dinero
What? Did you mean "Cuando sabrás la fecha de tu graduación".
La maestra nos da un examen
