7) -15/16 - (-9/24) = -6/8
8) 7/12 - 5/6 = 2/6
9) 2 1/4 - (-4 1/5) = 6 9/20
179)
-7,9 - 2,7 = -10,6
180)
2,9 - X = 14.7
-X = 14.7 - 2.9
X = -14.7 + 2.9
X= -11.8
181)
3 5/9 + (-2 1/4) - (-4 5/6) - 5 2/3
3 5/9 - 2 1/4 + 4 5/6 - 5 2/3 =
1) 3 5/9 - 2 1/4 = 1 4/5
2) 4 5/6 - 5 2/3 = -1 3/3
3) 1 4/5 + (-1 3/3) = 1/2