Final answer:
The fans of a turbofan engine can produce between 70% to 90% of the total thrust.
Step-by-step explanation:
The fans of a turbofan engine are capable of producing the majority of the thrust. The exact percentage of thrust generated by the fans can vary depending on the specific engine design and operating conditions. However, in a typical turbofan engine, the fans can produce between 70% to 90% of the total thrust. For example, the GE90-110B1 turbofan engine, which is mounted on a Boeing 777, is capable of producing thrusts of 330-510 kN. The fans in this engine contribute a significant portion of the total thrust.