1.
x+1/15=-1/5 => x=-1/15-3/15 => x=-4/15
2. -5,7y = -1,9 => 5,7y = 1,9 => y = (19/10) / (57/10) => y = (19/10) * (10/57) => y = 19 / 57
3. -5,6y + 7,3= -15,1 => 5,6y - 7,3= 15,1 => 5,6y = 15,1 + 7,3 => 5,6y = 22,4y = (224/10)*(10/56) => y = 224/56 => y= 4