Mach 0.80 (530 mph or 458 knots) at 35,000 ft.
At cruise altitude (35,000ft) the average cruise speed is 460 knots - 530mph.
155 knot average
Its top speed, according to Boeing, is 609 mph
a fully loaded 757-200 has a range of 7600kilometers if equipped with winglets, the cruise speed of this model is about 850km/h 7600/850= 8.94 almost 9hours when cruising on a full tank
138 knots average
it is commonly 140 mph on average
from wikipediaCruise speed Mach 0.80 (530 mph, 458 knots, 850 km/h at cruise altitude, i.e. 35,000 ft or 10.66 km)
757
the cost of a Boeing 757-200 is $65 million and the cost of a 757-300 is $80 million
It honestly depends on what type of 757 you use. 757-200, -200F, -200WL, or -300 Boeing 757-200: 3,900 nautical miles Boeing 757-200F: 3,150 nautical miles Boeing 757-200WL: 4,100 nautical miles Boeing 757-300: 3,467 nautical miles
747
a Boeing 757 is a narrow body jet airliner