英语翻译an employee was promiseed ayearly rise of his salary of

英语翻译
an employee was promiseed ayearly rise of his salary of 4% in 2008 and 2009.but in2009 this rise was cut by 30%.find the percentage P of the total rise for these two years.

有一个工人,被许诺在2008年和2009年,工资每年递增4%.但是在2009年工资涨幅被减少了30%.求他的工资在两年里总共增长了百分之几（P）.
应该是这样做吧：
P=4%+4%(1+4%)(1-30%)