一、口算。
$4.3 - 0.25 = $ $0.82×0.3 = $ $6.5 - (0.6 + 2.5) = $
$9.6÷0.3 = $ $30.2 - 3.02 = $ $8.5 - 0.24 - 1.76 = $
$15×0.4 = $ $0.1÷0.5 = $ $1.5 + 0.25×4 = $
$1.24÷0.4 = $ $1.4×3 = $ $0.48 - 0.48÷12 = $
$0.72×0.5 = $ $2.6÷0.13 = $ $0.28÷0.4÷7 = $
$0.24 + 0.6 = $ $11.2×0.3 = $ $25×1.1 - 25 = $
$7a - 6a = $ $9x÷3 = $ $1.5÷0.3 - 0.2 = $
$0.83 + 0.38 = $ $15.2÷0.8 = $ $125×0.08×0.3 = $

4.05 0.246 3.4 32 27.18 6.5 6 0.2 2.5 3.1 4.2 0.44 0.36 20 0.1 0.84 3.36 2.5 a 3x 4.8 1.21 19 3

二、计算下面图形的面积。(每相邻两点之间的距离表示 1 cm)

$14÷2+4-1=10(cm^{2})$ $15÷2+1-1=7.5(cm^{2})$

解：第一个图形：$14÷2+4-1=10(cm^{2})$
第二个图形：$15÷2+1-1=7.5(cm^{2})$
答：两个图形的面积分别为$10cm^{2}$和$7.5cm^{2}$。