-7 целых 8/9-(-9 целых 1/6)
1 способ. - 7 ц. 8/9 - (- 9 ц. 1/6 ) = = - 7 ц. 16/18 + 9 ц. 3/18 = = 8 ц. 21/18 - 7 ц. 16/18 = = 1 ц. 5/18 2 способ. - 7 ц. 8/9 - (- 9 ц. 1/6 ) = = - (71/9 ) + (55/6) = =[ (55*3)/ (6*3) ] - [ (71*2)/(9*2) ]= = (165 - 142)/18 = = 23/18 = 1 ц. 5/18