1 直接写出得数。(每题1分,共20分)
$5.2 + 2.3 = $ $9.7 + 5 = $ $28.7 + 16 = $ $5.45 + 2.71 = $
$1.1 + 0.6 = $ $45.7 - 8.9 = $ $60×0.9 = $ $8.56 - 1.38 = $
$25.6 + 37.8 = $ $25 + 8.6 = $ $3.6÷10 = $ $2.8 + 5 = $
$5.1÷0.3 = $ $7.58 - 1.88 = $ $1.8 + 7.2 = $ $47 + 34.8 = $
$6.5×10 = $ $2.3×0.4 = $ $5×0.7 = $ $4.2×3 = $

7.5 14.7 44.7 8.16
1.7 36.8 54 7.18
63.4 33.6 0.36 7.8
17 5.7 9 81.8
65 0.92 3.5 12.6

2 计算下列各题,能简算的要简算。(每题3分,共18分)
$24×14.3 + 14.3×76$ $2.8×175 - 28×7.5$ $6.4 + 3.6×5.2$
$(2.5 + 0.25)×4$ $4.8×9.9$ $8×0.37×1.25$

1430 280 25.12
11 47.52 3.7

3 解方程。(每题4分,共12分)
$2x - 0.15 = 6.25$ $0.35 + 0.5x = 36.6$ $3(x - 2.1) = 8.4$

解:$x=3.2$ 解:$x=72.5$ 解:$x=4.9$