Question 829755
This suggests a linear equation with a negative slope.  This is with y intercept 150, for when s for steps downward is zero.


Vertical axis, y, the height on the hill.
Horizontal axis, s, for steps count.

We can make an equation in slope-intercept form.  What is the slope?
Vertical change of -0.25 occurs with horizontal change of +1.
Slope, is {{{-0.25}}} or if prefered, {{{-(1/4)}}};


EQUATION: {{{highlight(y=-(1/4)s+150)}}}
Half-way down the hill is at {{{y=150/2=75}}}; substitute it, and solve for s.
(Alternatively, solve for s and then substitute for y=75).