A shop sells laptops at $600 each and a smartphone at $400.  Celine buys two laptops and four smartphones for her children. How much change does she get back if she has $3000?
The cost of the two laptops is 2 x $600 = $
<gadget id="calculator">2*600</gadget>
<output>1_200</output>
1200.
The cost of the four smartphones is 4 x $400 = $
<gadget id="calculator">4*400</gadget>
<output>1_600</output>
1600.
Thus, the total cost of all the items is $1200 + $1600 = $
<gadget id="calculator">1200+1600</gadget>
<output>2_800</output>
2800.
Therefore, Celine gets a change of $3000 - $2800 = $
<gadget id="calculator">3000-2800</gadget>
<output>200</output>
200.

<result>200</result>