Formerly called or formerly known as are the common ways to say this in ae (american english). He along with two of his workmates founded. Formerly is the only one that can go there.
I'd normally expect formerly which is short for formerly known as bombay or which was formerly bombay. In english, when we talk about a company or other entity that has a new name, we use the phrase formerly known as or f/k/a to indicate the previous name. Please tell us your full sentence.
In a case study session, my professor told me that the following sentence was wrong due to its misuse of the word formerly. To my understanding 'former'is an adjective on director and 'formerly' is an adverb on was, so both can work. Staff mistakenly transferred the total $1,000 dollar (formerly/originally/ initially deposited to the wrong account number 123) to 456 whenthe $500 should have been. Depending on how you use it,.