Question

Are these sentences grammatically correct? Tenemos tantos bolígrafos como ellas. Son tan altos como nosotros.

Answer 1

I believe the correct sentence structure should go as followed.

"Tenemos tantos bolígrafos como ellas. Son tan altas como nosotros."

If your sentence means "We have as much pens as they do. They are as tall as us." ("They" in this case referring to a plural amount of individuals being of the female gender.)

However, there are better ways to rewrite the sentence in Spanish in order to sound more articulate and less choppy in my opinion.

Let me know in the comments if you have any questions or need any additional help! :)

Answer 2

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.