4y-(3y-(2y-(y+1))) ребят плиииииззззз
4y - ( 3y - ( 2y - ( y + 1 ))) = 4y - ( 3y - ( 2y - y - 1 )) = 4y - ( 3y - ( y - 1 )) = 4y - ( 3y - y + 1 ) = 4y - ( 2y + 1 ) = 4y - 2y - 1 = 2y - 1