Which of the following is a speed, not a velocity?
a.
35 m/s east
b.
–35 m/s
c.
35 m/s
d.
35 m/s south

Velocity is a vector quantity which means that it has both magnitude and direction.
Speed is a scalar quantity which only is defined by its magnitude.
(magnitude refers to its numerical value or absolute value)
Because speed is a scalar quantity it will not have a direction which means that answer A and answer D are wrong because they have the direction of east and south. The answer is choice C. 35m/s and not B. -35m/s because speed cannot be a negative value.(note that while speed cannot be negative velocity can)

Answer: fn = wcos50 = 38.89(9.81)(cos50) = 245.23 n