The percentage of increase was 87.027... %
<em><u>Explanation</u></em>
The value of U.S exports to China increased from $1480 million to $2768 million.
Suppose, the percentage of increase is 
So, <u>the amount of increase</u> =
of 1480 
Thus, the equation will be......

So, the percentage of increase was 87.027... %
15:10
3:2
Hope this helps :)