At the beginning of 2009,Miss Wong deposited a sum of money in a bank at an interest rate of 8％ p.a.compounded yearly.If
问题描述：
At the beginning of 2009,Miss Wong deposited a sum of money in a bank at an interest rate of 8％ p.a.compounded yearly.If the interest she will receive at the beginning of 2011 is 12480,find（a）the principal
（b）the amount she can receive at the beginning of 2014.
答
2009年初,王女士存入银行一笔钱,年利率 8%,以复合利率计算,2011年初王女士收到利息12480,则(1)金是?(2)2014年初她可以得到多少?
设本金为x
x*(1+8%)的平方=12480+x
复利计算方式：本金P*（1+利率）的（年数）次方=本金+利息
(1)x本金=75000
(2)2014年=x*(1+1.08)的五次方=110199.6请问能把第一步的计算步骤写出来吗？