Answer
There are 195,140 thousand personal computers in China.
There are 310,640 thousand personal computers in the US.
Work Step by Step
Let $c$ be the personal computers in China.
The personal computers in the US are $c+115500$.
$c+(c+115500)=505780$ $\longrightarrow$combine like terms
$2c+115500=505780$ $\longrightarrow$addition property
$2c+115500-115500=505780-115500$ $\longrightarrow$simplify
$2c=390280$ $\longrightarrow$multiplication property
$2c\div2=390280\div2$ $\longrightarrow$simplify
$c=195140$
$c+115500=195140+115500=310640$
