The phrase "a protest by three" is correct and usable in written English.
It can be used to describe a protest that is organized or participated in by three individuals or groups.
Example: "The news reported on a protest by three who were advocating for climate change awareness in the city."
Alternatives: "a demonstration by three" or "a rally by three".
Mr. Ayrault's statement followed a protest by two large home-improvement chains in the Paris region that remained open this Sunday in defiance of a court ruling.
A massive security operation was mounted in the Chinese capital, but there were several small demonstrations by homeowners who had their houses bulldozed to make way for the games and a protest (by four Westerners) over the status of Tibet.
On this occasion the reason appears to have been a protest by two monks who immoliated themselves, leading to a tighter military crackdown in Aba (known as Ngaba in Tibetan), which neighbours Ganzi.
A protest by nine Mexican immigrants in which they tried to enter the country through a border station in Arizona even though they had no valid documents has provoked an unusual public argument among groups pushing Congress to overhaul the immigration laws.
We had a cup of coffee a day or two before the Super Bowl and he told me that there would be a protest by several hundred Indians at the stadium.
A protest by several hundred people in the city's central plaza, People's Square, moved southward into Uighur areas, including the Grand Bazaar, a large shopping centre.
Last month, government police officers wounded two guards and detained two others in a raid on the home of a Sunni, Sheik Albo Baz, in Salahuddin Province, prompting a protest by several thousand Sunnis in Samarra, a city divided by sect.
The clashes, which broke out during a protest by several hundred Christians over the burning last week of a church in the village of Soul, were a significant departure from the sense of solidarity that had prevailed among people of different backgrounds throughout the weeks of protests that led to Mr. Mubarak's resignation.
A meeting of the City Council education committee in City Hall was disrupted yesterday by a protest by about two dozen adults and school children objecting to what they described as racist and white supremacist remarks by the committee's new chairman.
Kevin Thomson and Jason Cummings both had penalties saved to seal Hibs' fate, sending Hamilton Accies up to the Premiership and sparking a protest by several hundred angry Hibs fans outside the stadium following the final whistle.
