题目

When we talk about intelligence, we do not mean the ability to get good scores on certain kinds of tests or even the ability to do well in school subjects. By intelligence we mean a way of living and behaving, especially in a new or upsetting situation. If we want to test intelligence, we need to find out how a person acts instead of how much he knows what to do. For instance, when in a new situation, an intelligent person thinks about the situation, not about himself or what might happen to him. He tries to find out all he can, and then he acts immediately and tried to do something about it.某居民生活用电基本价格为每度0.50元，若每月的用电量超过a度，超出部分比基本电价增加20%收费．（1）某户五月份用电84度，共交电费44.4元，求a的值；（2）若该户六月份的电费平均为每度0.54元，该用户六月份共用电多少度？应交电费多少元？