一、口算。
6.18÷0.6 = 3.5×1.2 = 0.5 + 0.5÷0.5 =
2 - 0.25 = 6÷0.4 = (2.72 - 2.7)×3.5 =
0.72÷9 = 40×0.04 = 2.1×40÷10 =
1.3×7 = 3 - 1.53 = 1.8×0.4×0.25 =
0.12÷0.3 = 0.72 + 0.89 = 1.36 + 2.87 + 3.64 =
2.4×1.25 = 5.4÷0.6 = 1.2×(5÷0.25) =
1.8÷0.15 = 1.05 + 3.45 = 26.1 - 3.5 - 7.5 =
0.63 - 0.36 = 4.5×0.2 = (0.03 + 0.12)÷1.5 =
0.38×3 = 10.2 - 9.45 = 37.2×99 + 37.2 =
3.6 + 7.4 = 100÷1000 = 17.2 - (8.15 + 7.2) =

10.3 4.2 1.5
1.75 15 0.07
0.08 1.6 8.4
9.1 1.47 0.18
0.4 1.61 7.87
3 9 24
12 4.5 15.1
0.27 0.9 0.1
1.14 0.75 3720
11 0.1 1.85

二、解方程。
0.15x + 0.2x = 3.22 0.52x - 2.8 = 7.6 0.9x + 4×2.5 = 18.1

$x = 9.2$ $x = 20$
$x = 9$