Igor had three brothers and no sisters.
There were many inventors of helicopters. I believe Igor Sikorsky was the best.
A Russian-American, Igor Sikorsky, invented the first working helicopter...however, Leonardo Da Vinci created the concept of a helicopter many years before Sikorsky was born.
He had 11 brothers and sisters.
There are 4 brothers and 3 sister's all up. Assume your one of the brothers - hence you have 3 brothers and 3 sisters. However any one of your sisters, would have 4 brothers and 2 sisters.
There are three brothers and two sisters.
One sister, two brothers
2 brothers and sisters
Athena had no brothers or sisters.
he had no brothers or sisters
One brother, two sisters ( if you're the second brother)
Sikorsky had designed many different aircraft. The helicopter was the epitome of his career