Martha wants to buy a digital camera from her 3 month savings. To do this she needs to maintain an average saving of 300.00 in each month. She saves 450.00 in the first month and 200.00 in the second month. Find the amount she should save in the third month , in dollars , to buy a digital camera at the end of three months.
<gadget id="calculator">300 * 3</gadget>
<output>900</output>

<gadget id="calculator">450 + 200</gadget>
<output>650</output>

<gadget id="calculator">900 - 650</gadget>
<output>250</output>

<result>250</result>