1.
1) -18 3/5 - 20,1 = - 18 6/10 - 20 1/10 = - 38 7/10
2) - 38 7/10 : (-0,3) = - 387/10 * (-10/3 ) = 387/3 = 129
2.
1) 3 2/5 : 17/20 = 17/5 * 20/17 = 20/5 = 4
2) 4,5 - 4 = 0,5
3.
1) 1,8 + 3,2 = 5
2) 3,75 : 5 = 0,75
3) 21 - 0,75 = 20,25
4.
1) 1,08 * (-7,5) = -8,1
2) 1,9 - (-8,1) = 1,9+8,1 =10
3) 10 : 3 1/4 = 10 * 4/13 = 40/13 = 3 1/13
5.
1) -5/9 + 14/15 = = -25/45 + 42/45 = 17/45
2) 17/45 : (-17/30) = 17/45 * (-30/17) = - 30/45 = - 6/9
6.
1) 7 1/2 - 4,25 = 7 1/2 - 4 25/100 = 7 1/2 - 4 1/4 = 7 2/4 - 4 1/4 = 3 1/4
2) 3 1/4 : 9/20 = 13/4 * 20/9 = 260/36 = 65/9 = 7 2/9
3) 3 1/3 + 7 2/9 = 3 3/9 + 7 2/9 = 10 5/9
7.
1) 4 2/3 - 3 7/9 = 4 6/9 - 3 7/9 = 42/9 - 34/9 = 8/9
2) 3,6 * 8/9 = 3 6/10 * 8/9 = 3 3/5 * 8/9 = 18/5 * 8/9 = 16/5 = 3 1/5
3) 3 1/5 + 5,8 = 3 1/5 + 5 8/10 = 3 1/5 + 5 4/5 = 8 5/5 = 9