Find area under and above the curve with horizontal line and its min/max values in a given range of line ?

I want to do following tasks,

First generate a time series load data between 550-1000 for one day 30 min interval, so load(48*1) dataset

then set level_1 = 750 and draw a line on the graph,

then find out the area above this level_1 line and area under seprate level (lets say level_2 = 600) line seprately.

Then Can we find the min or max area if the Level_2 vary between the range of [600 800], find at which point the area(under the Level_2) is min or max?

with another constraint is that

area_1 - area_2 + K >= 0; % K is constant and lets say K= 800 ( 80% of max load)