(4/5-x)+13/20=25/30
( 4\5 - X ) = 25\30 - 13\20 = 50\60 - 39\60 = 11\60 X = 4\5 - 11\60 X = 48\60 - 11\60 X = 37\60
(4/5-х)+13/20=25/30 4/5-х=25/30-13/20 4/5-х=50-39/60 4/5-х=11/60 х=4/5-11/60 х=48-11/60=37/60 х=37/60