Pls ! i don’t understand this at all

Part A
 Company P
 We have the slope is:
 m = (y2-y1) / (x2-x1)
 m = (198-150) / (1650-1250)
 m = 0.12 $ / kwh
 Company M
 The slope of the line is what we should look for in this case.
 The line is:
 y = 0.15x
 The slope is:
 m = 0.15 $ / kwh
 Part B
 Company P
 The line is:
 y-150 = 0.12 (x-1250)
 Rewriting:
 y = 0.12x - (0.12 * 1250) + 150
 y = 0.12x
 Company M 
  y= 0.15x
 We note that company P is cheaper.
 The cost of generating 2375 Kwh is:
 y = 0.12x
 y = 0.12 * (2375)
 y = $ 285
 
 Company P:
 y = $ 285

Add them all together then u will get your answer