Erika is saving for a new laptop. The laptop she wants costs $600. The sales assistant told her that if she traded in her old laptop, the price of the new one would be reduced by $200. She thinks this is a good deal and agrees to do it. She already has some savings in her purse, and has also been paid $150 this week for her part-time job. Her mom agrees to give her $80 to help her. If Erika now only needs an extra $50 to buy the laptop, how much money does she have in her purse?
Selling the old laptop reduced the cost of the new laptop to $600 - $200 = $
<gadget id="calculator">600-200</gadget>
<output>400</output>
400 dollars.
We know she doesn't have all the money yet, so she actually has $400 - $50 = $
<gadget id="calculator">400-50</gadget>
<output>350</output>
350 dollars.
Some of this money came from her mom, so the money she had herself was $350 - $80 = $
<gadget id="calculator">350-80</gadget>
<output>270</output>
270.
Subtracting her part-time wages shows that she had $270 - $150 = $
<gadget id="calculator">270-150</gadget>
<output>120</output>
120 in her purse.

<result>120</result>