60 ! решите уравнение (2целых 2/3x+1целая 3/7x)*21=

(2 2/3 х +1 3/7 х)*21=58
(2 14/21 х + 1 9/21 х)* 21=58
(3 23/21 х)*21=58
4 2/21 х*21=58
86/21 х * 21=58
86х=58
х=58/86
х=29/43

( 2 ( 2/3 )Х + 1 ( 3/7)Х ) * 21 = 58 
2 ( 2/3)X + 1 ( 3/7 )X = 58 : 21 
2 ( 14/21 )X + 1 ( 9/21 )X = 58/21 
( 56/21 )X + ( 30/21 )X = 58/21 
56X + 30X = 58 
86X = 58
X = 58/86 
X = 29/43