Ben's new car cost twice as much as his old car. He sold his old car for $1800 and used that to pay off some of the cost of his new car. He still owes another $2000 on his new car. How much did his old car cost, in dollars?
His new car costs 1800+2000=
<gadget id="calculator">1800+2000</gadget>
<output>3_800</output>
3800 dollars.
His old car cost 3800/2=
<gadget id="calculator">3800/2</gadget>
<output>1_900</output>
1900 dollars.

<result>1_900</result>