In year Y imported machine tools accounted for 25 percent of total machine-tools sales in the United States, and Japanese imports accounted for 45 percent of the sales of imported machine tools. If the total sales of machine tools imported from Japan that year was x billion dollars, then the total sales of all machine tools in the United States was how many billion dollars?

A. $\frac{9x}{80}$

B. $\frac{13x}{20}$

C. $\frac{80}{9x}$

D. $\frac{20x}{13}$

E. $\frac{80x}{9}$