(1)12×5÷2+(8+12)×5÷2
=30+50
=80(平方厘米);[来源:学|科|网Z|X|X|K]
(2)2×3.2-(0.5+2)×0.8÷2
=6.4-1
=5.4(平方米)
23.x=3;x=0.1;x=8
x=8.7;x=1.1;x=15
(1)4.2×5+3x=30
解:21+3x=30
3x=30-21
3x=9
x=9÷3
x=3
(2)6x-1.4x=0.46
解:4.6x=0.46
x=0.46÷4.6
x=0.1
(3)4x+2.5x=52
解:6.5x=52
x=52÷6.5
x=8
(4)(x-5.5)×8=25.6
解:x-5.5=25.6÷8
x-5.5=3.2
x=3.2+5.5
x=8.7
(5)32-16x=14.4
解:16x=32-14.4
16x=17.6
x=17.6÷16
x=1.1
(6)(x+2.6)÷4=4.4
解:x+2.6=4.4×4
x+2.6=17.6
x=17.6-2.6
x=15
24.1 72.72 23
25.17株
36÷2﹣1