Question: I'm stuck on this math problem: 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?
Can you help?
Answer: 
The cost of the two laptops is 2 x $600 = $1200.
The cost of the four smartphones is 4 x $400 = $1600.
Thus, the total cost of all the items is $1200 + $1600 = $2800.
Therefore, Celine gets a change of $3000 - $2800 = $200.