心算
5x + 12x =17x 19a - 8a = 11a 5.7b + 6.2b =11.9b
16x - 2x = 14x 32a + 9a = 41a 8.3b - 5.2b =3.1b
20.3t + 12.5t =32.8t 4.3x - 2.1x =2.2x 7.5a - 3.4a =4.1a
x 丶x = 4a × 5 = 20a 6a + 5a =11a
12y + 8y =20y 3x × 0 = 0 a×a×a =a³
9.4x + 6.6x =16x 16t - 13.4t = 2.6t 12x -8.3x =3.7x
2.笔算（解下列方程）
10x - 25 =30 x=5.5 0.5x + 28 =52 x=48 8x -36 = 42 x=39/4
9.25 + 2x =22.35 x=6.55 3.5x - 6 =4.5 x=3 6.5x + 9 =28.5 x=3