Question 1093560
x, time in hours
y, cost


<s>{{{y=500}}} for {{{0<x<=2}}}</s>
and
<s>{{{cross(y=500+100x)}}} for {{{x>2}}}</s>


{{{cross(100x+500<=900)}}}
If first two hours already used, then {{{highlight(100(x-2)+500<=900)}}}