8a+2a=
2×n×n=
3m-3m=
5b-b=
0.4÷0.2= 1÷= 406﹣299= a﹣a×0=
所挂重物的质量/Kg
0
1
2
3
4
5
6
7
弹簧的长度/cm
12
12.5
13
13.5
14
14.5
15
15.5