Use the following information to answer this question. If nominalGDP rises from $100 trillion to $120 trillion, while the GDPdeflator rises from 2.0 to 2.2, the percentage change in real GDPis approximately equal to？ 答案为什么是0啊我的计算式：(120/2.2-100/2)/(100/2)  问题又出在哪里呢？