287+367=?,189+493=?,303+739=?
689-62=?,951-564=?,969-288=?
94+?=621,533+?=773,204+?=948
69*7=?,83*4=?,108*9=?
252/9=?,900/6=?,788/4=?
---
?-278=874-401,112+156+493+149=?
733-296=?+320,505+375+232-932=?
270+?+385=927,411+224-187-382=?
210+?-461=373,999-349-109-397=?
值得信任吗