Combine these 2 sentences with an adverbial clause:

The mountain was breathtaking. We took a picture of it.

Here's a list of subordinating conjunctions:

http://grammar.ccc.commnet.edu/grammar/conjunctions.htm#subordinating_conjunctions

Figure out which one would work best and let us know how you decide to combine those two sentences.

We'll be glad to check your answer.

http://www.grammar-monster.com/glossary/adverbial_clauses.htm

To combine these two sentences with an adverbial clause, we need to find a way to connect the idea of taking a picture to the description of the mountain. One way to do this is by using the adverbial clause "while taking a picture of it."

The sentence combining the two sentences would be:

The mountain was breathtaking while we took a picture of it.