(1)24+42=
(2) ﹣ =
(3)0.56÷0.7=
(4) ×0+ =
(5)20%×5=
(6) ×6=
(7)9.9n+0.1n=
(8)1÷0.25÷40=
杨洋猜想:(a+b)+c=a+c+b+c。李宏猜想: a+(b+c)=a+c+b+c.