1/5а + 1/4а = 4/20а + 5/20а = 9/20а
5/м+6 - 15-4м/36-м2 = 5(6-м)/36-м2 - 15-4м/36-м2 = 30-5м-15+4м/36-м2 = 15-м/36-м2
1/5а + 1/4а = 4/20а + 5/20а = 9/20а
5/м+6 - 15-4м/36-м2 = 5(6-м)/36-м2 - 15-4м/36-м2 = 30-5м-15+4м/36-м2 = 15-м/36-м2