1) 2/3 : (-2) = -2/3 * 1/2 = -1/3
2) (-3/4) : 1 1/2 = (-3/4) : 3/2 = -3/4 * 2/3 = -1/2 = -0,5
3) -4/5 : 8 = -4/5 * 1/8 = -1/10 = -0,1
4) 4 : (-1/2) = -4 * 2 = -8
5) 5 : (-5/8) = -5 * 8/5 = -8
6) (-6) : (-3/5) = 6 * 5/3 = 10
7) (-5/6) : (-5/12) = 5/6 * 12/5 = 2
8) -3 3/4 : 1 1/2 = -15/4 : 3/2 = -15/4 * 2/3 = -5/2 = -2,5
9) 1 7/9 : (-2 2/3) = 16/9 : (-8/3) = -16/9 * 3/8 = -2/3
10) (-8 2/5) : 7 = -42/5 * 1/7 = -6/5 = -1 1/5 = -1,2
11) (-7 1/2) : (-5) = 15/2 * 1/5 = 3/2 = 1 1/2 = 1,5
12) 4 2/3 : (-1 1/6) = 14/3 : (-7/6) = -14/3 * 6/7 = -4
число десятков = 8
485-80=405