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一、口算。
$8 - 1.6 =$
$0.12×8 =$
$7.92 + 2.08 =$
$4.2 - 2.02 =$
$1÷0.05 =$
$200 - 160 =$
$0.22 + 0.8 =$
$10 - 2.05 =$
$0.24÷0.3 =$
$1.5 - 0.67 =$
$2.5×2.4 =$
$0.88÷0.8 =$
$0.49 + 2.8 =$
$0.54÷1.8 =$
$0.7×2.6 =$
$9×12 =$
$1.78 - 0.7 =$
$4.8÷0.12 =$
$1.32 + 2.08 =$
$33.5÷5 =$
$108 + 23 =$
$0.24×0.5 =$
$75÷25 =$
$0.72÷0.4 =$
$8 - 1.6 =$
6.4
$0.12×8 =$
0.96
$7.92 + 2.08 =$
10
$4.2 - 2.02 =$
2.18
$1÷0.05 =$
20
$200 - 160 =$
40
$0.22 + 0.8 =$
1.02
$10 - 2.05 =$
7.95
$0.24÷0.3 =$
0.8
$1.5 - 0.67 =$
0.83
$2.5×2.4 =$
6
$0.88÷0.8 =$
1.1
$0.49 + 2.8 =$
3.29
$0.54÷1.8 =$
0.3
$0.7×2.6 =$
1.82
$9×12 =$
108
$1.78 - 0.7 =$
1.08
$4.8÷0.12 =$
40
$1.32 + 2.08 =$
3.4
$33.5÷5 =$
6.7
$108 + 23 =$
131
$0.24×0.5 =$
0.12
$75÷25 =$
3
$0.72÷0.4 =$
1.8
答案
一、6.4 0.96 10
2.18 20 40
1.02 7.95 0.8
0.83 6 1.1
3.29 0.3 1.82
108 1.08 40
3.4 6.7 131
0.12 3 1.8
2.18 20 40
1.02 7.95 0.8
0.83 6 1.1
3.29 0.3 1.82
108 1.08 40
3.4 6.7 131
0.12 3 1.8
二、解方程。
$x + 8 - 6 = 12$
$20x÷4 = 25$
$1.3x + 7.2 = 12.4$
$2.8 + 7x = 5.6$
$0.5x - 2.4 = 2.6$
$10 + 4x = 10.8$
$x + 8 - 6 = 12$
$20x÷4 = 25$
$1.3x + 7.2 = 12.4$
$2.8 + 7x = 5.6$
$0.5x - 2.4 = 2.6$
$10 + 4x = 10.8$
答案
方程$x + 8 - 6 = 12$
解：
$x+8 - 6 = 12$
$x+(8 - 6)=12$
$x + 2 = 12$
$x=12 - 2$
$x = 10$
方程$20x÷4 = 25$
解：
$20x÷4 = 25$
$20x=25×4$
$20x = 100$
$x = 100÷20$
$x = 5$
方程$1.3x + 7.2 = 12.4$
解：
$1.3x+7.2 = 12.4$
$1.3x=12.4 - 7.2$
$1.3x = 5.2$
$x = 5.2÷1.3$
$x = 4$
方程$2.8 + 7x = 5.6$
解：
$2.8+7x = 5.6$
$7x=5.6 - 2.8$
$7x = 2.8$
$x = 2.8÷7$
$x = 0.4$
方程$0.5x - 2.4 = 2.6$
解：
$0.5x-2.4 = 2.6$
$0.5x=2.6 + 2.4$
$0.5x = 5$
$x = 5÷0.5$
$x = 10$
方程$10 + 4x = 10.8$
解：
$10+4x = 10.8$
$4x=10.8 - 10$
$4x = 0.8$
$x = 0.8÷4$
$x = 0.2$
综上，方程$x + 8 - 6 = 12$的解为$x = 10$；方程$20x÷4 = 25$的解为$x = 5$；方程$1.3x + 7.2 = 12.4$的解为$x = 4$；方程$2.8 + 7x = 5.6$的解为$x = 0.4$；方程$0.5x - 2.4 = 2.6$的解为$x = 10$；方程$10 + 4x = 10.8$的解为$x = 0.2$。
解：
$x+8 - 6 = 12$
$x+(8 - 6)=12$
$x + 2 = 12$
$x=12 - 2$
$x = 10$
方程$20x÷4 = 25$
解：
$20x÷4 = 25$
$20x=25×4$
$20x = 100$
$x = 100÷20$
$x = 5$
方程$1.3x + 7.2 = 12.4$
解：
$1.3x+7.2 = 12.4$
$1.3x=12.4 - 7.2$
$1.3x = 5.2$
$x = 5.2÷1.3$
$x = 4$
方程$2.8 + 7x = 5.6$
解：
$2.8+7x = 5.6$
$7x=5.6 - 2.8$
$7x = 2.8$
$x = 2.8÷7$
$x = 0.4$
方程$0.5x - 2.4 = 2.6$
解：
$0.5x-2.4 = 2.6$
$0.5x=2.6 + 2.4$
$0.5x = 5$
$x = 5÷0.5$
$x = 10$
方程$10 + 4x = 10.8$
解：
$10+4x = 10.8$
$4x=10.8 - 10$
$4x = 0.8$
$x = 0.8÷4$
$x = 0.2$
综上，方程$x + 8 - 6 = 12$的解为$x = 10$；方程$20x÷4 = 25$的解为$x = 5$；方程$1.3x + 7.2 = 12.4$的解为$x = 4$；方程$2.8 + 7x = 5.6$的解为$x = 0.4$；方程$0.5x - 2.4 = 2.6$的解为$x = 10$；方程$10 + 4x = 10.8$的解为$x = 0.2$。
