1. 直接写出得数。
3.8 + 2 = 12.5 - 0.8 = 0.28×5 = 3.5÷(0.2 + 0.3) =
5.2 - 2.71 = 2.7×30 = 16×0.2 = 45÷1.5×0.3 =
3.7 + 7.3 = 12.5÷5 = 0.03×40 = 0.6÷0.03÷0.2 =
7.5 - 7.05 = 3.2×4 = 5.1 - 1.7 = 0.3×6÷2 =
2.8 + 3.29 = 3.85 + 2.7 = 0.32÷0.4 = 0.28÷0.7 + 2.3 =
4.2×0.2 = 1.1×0.9 = 7.2 + 0.9 = 1.2÷0.6×0.1 =
2.3 - 1.8 = 88÷110 = 14.2 - 7.8 = 1.7×9 + 1.7 =
3.02 + 4.8 = 5 - 0.85 = 4.6×0.1 = 0.8×8÷2 =

1. 5.8 11.7 1.4 7 2.49 81 3.2 9 11 2.5 1.2 100 0.45 12.8 3.4 0.9 6.09 6.55 0.8 2.7 0.84 0.99 8.1 0.2 0.5 0.8 6.4 17 7.82 4.15 0.46 3.2

2. 解方程。
x÷1.2 = 12 20 + 2x = 170 x + 0.92 = 1.07 + 0.8
6x - 4.2x + 7 = 16 (x + 1.6)÷4.5 = 4.8 4×9.5 - 4x = 30

2. $ x = 14.4 $ $ x = 75 $ $ x = 0.95 $ $ x = 5 $ $ x = 20 $ $ x = 2 $

明明在计算(x + 0.79)×1.9 时，漏看了括号，算出的结果比正确结果小 0.27，则正确结果应该是多少？

思维提升
$ (x + 0.79) × 1.9 - (x + 0.79 × 1.9) = 1.9x - x = 0.9x $ $ 0.9x = 0.27 $ $ x = 0.3 $ $ (x + 0.79) × 1.9 = (0.3 + 0.79) × 1.9 = 2.071 $