easy to understand

You have to put the facts into a form that's understandable to everyone. 你得把这些事实用一种大家都能理解的形式表达出来。

You say that something, for example someone's behaviour, is understandable, if you feel that it is usual and not strange or difficult to understand

Their refusal to cooperate is perfectly/completely understandable, considering the circumstances. 考虑到各种因素，他们拒绝合作是完全可以理解的。