Ответ:

Пошаговое объяснение:

В - 1 .

1 . а) 3/7 * 2/5 = ( 3*2 )/( 7*5 ) = 6/35 ; в) 3 1/9 * 2 1/7 = 28/9 * 15/7 = 20/3 = 6 2/3 ;

б) 7/13 * 39/56 = ( 7*39 )/( 13*56 ) = 3/8 ; г) 1 7/8 *3,2*2 1/3 = 15/8 *32/10 *7/3 = 14 .

2 . ( 0,8 - 2/3 )* 2 1/2 + 2 = 2 1/3 .

1) 0,8 - 2/3 = 4/5 - 2/3 = 12/15 - 10/15 = 2/15 ;

2) 2/15 * 2 1/2 = 2/15 * 5/2 = ( 2 * 5 )/( 15 * 2 ) = 1/3 ;

3) 1/3 + 2 = 2 1/3 .