Решить 1/2-(+4); - целых 1/3); 18,7-(+20целых 1/4)

1) ( 1/2 ) - ( + 4 ) = ( 1/2 ) - 3 ( 2/2 ) = - 3 ( 1/2 ) ;
2) - 5 - ( - 2 ( 1/3 ) ) = - 4 ( 3/3 ) + 2 ( 1/3 ) = - 2 ( 2/3 ) ;
3) 18,7 - ( + 20 ( 1/4 ) = 18 ( 7/10 ) - 20 ( 1/4 ) = 18 ( 14/20 ) - 20 ( 5/20 ) = 18 ( 14/20 ) - 19 ( 25/20 ) = - 1 ( 11/20 ) ;

1/2-(+4)=1/2-4=1/2-8/2=-7/2=-3ц 1/2
-5-(-2ц.1/3) = -15/3+7/3= -8\3=-2ц. 2/3