Dawn and aram have stretched a slinky between them and begin experimenting with waves. as the frequency of the waves is doubled the wavelength

Iassume the answer is 75 feet. inwards to outwards rather than outwards to inwards. probably be 75.hachures are stokes drawn in direction of the steepest slope. a series of short parallel lines drawn on a map to indicate topographic relief. it is actually called hachures on contour lines. the small marks in the center of the feature are called hachures.observe the picture attached

From my calculation, i got 3.655moles