Ross and Kristen disagreed about how to write an equation to represent the following situation.

Ross had twice as many DVDs as kristen. Together they had 93 DVDs. How many did Kristen have?

They agreed that x should represent the number of DVDs that Kristen had. Ross wrote the equation x+2x=93,while Kristen wrote the equation 2x=93. whose equation is correct? Explain your choice.