How fast is a wave moving if it has a frequency of 35 hz and there are 6 meters between crests ?

Anybody wanna ? (picture included? )

Henry, whose mass is 95 kg, stands on a bathroom scale in an elevator. the scale reads 830 n for the first 2.4 s after the elevator starts moving, then 930 n for the next 2.4 s. part a what is the elevator's speed 4.8 s after starting? express your answer with the appropriate units.

If angle "a" is 25°, angle "b" is: a) equal to angle c b) less than angle c c) greater than angle c