1)10: 1 7/8=8x-2x-3x 2)3 2/45x+1 7/30x=6 1/9 3)(8 2/5: x+3 5/9): 4 1/6=1 1/3 4)(5 1/6-x)•2 7/10-1 3/14=3 2/7

10 : 1 ( 7/8 ) = 8x - 2x - 3x  10 : ( 15/8 ) = x * ( 8 - 2 - 3 )  80/15 = x * 3  x = ( 16/3  ) : 3  x = 16/9  x = 1 ( 7/9 )  3 ( 2/45 ) x + 1 ( 7/30 ) x = 6 ( 1/9 )  (137/45 ) x + ( 37/30 ) x = 55/9 ( 274/90 ) x + ( 111/90 ) x = 550/90  274x + 111x = 550  385x = 550  x = 1 ( 165/385 )  x = 1 ( 33/77 ) x = 1 ( 3/7 ) ( 8 2/5 : x + 3 5/9 ) : 4 ( 1/6 ) = 1 (  1/3 ) 8 ( 2/5 ) : x + 3 ( 5/9 ) = 1 ( 1/3 ) * 4 ( 1/6 )  8 ( 2/5 ) : x + 3 ( 5/9 ) = ( 4/3 ) * ( 25/6 )  8 ( 2/5 ) : x + 3 ( 5/9 ) = 50/9  8 ( 2/5 ) : x = 5 ( 5/9 )  - 3 ( 5/9 )  8 ( 2/5 ) : x = 2  x = 8 ( 2/5 ) : 2  x = 8,4 : 2  x = 4,2  ( 5 1/6 - x ) * 2 ( 7/10 ) - 1 ( 3/14 ) = 3 ( 2/7 )  ( 5 1/6 - x ) * 2 ( 7/10 ) = 3 ( 2/7 ) + 1 ( 3/14 )  ( 5 1/6 - x ) * 2 ( 7/10 ) = 3 ( 4/14 ) + 1 ( 3/14 )  ( 5 1/6 - x ) * 2 ( 7/10 ) = 4 ( 1/2  )  5 ( 1/6 ) - x = 4 ( 1/2 ) : 2 ( 7/10 )  5 ( 1/6 ) - x = ( 9/2 ) : ( 27/10 )  5 ( 1/6 ) - x   = 1 ( 2/3 )  x = 5 ( 1/6 ) - 1 ( 2/3 )  x = 4  ( 7/6 ) - 1 ( 4/6 )  x = 3 ( 1/2 ) 

13-7b.