This morning, farmer Rita's workers collected 30,000 gallons of milk and chilled it in a storage tank. They then spent the next 4 hours pumping milk at a rate of 2,880 gallons/hour from the storage tank into a milk tanker. For the next 7 hours, the workers added more milk into the storage tank, at a rate of 1,500 gallons per hour. How many gallons of milk were left in the storage tank?
In the first 4 hours, the milk tanker got 4 hours * 2880 gallons/hour = 
<gadget id="calculator">4*2880</gadget>
<output>11_520</output>
11,520 gallons.
Thus, the storage tank was left with 30,000 gallons - 11,520 gallons = 
<gadget id="calculator">30000-11520</gadget>
<output>18_480</output>
18,480 gallons.
For the next 7 hrs, the workers added 1,500 gallons/hour * 7 hours = 
<gadget id="calculator">1500*7</gadget>
<output>10_500</output>
10,500 gallons.
The total therefore is 18,480 gallons + 10,500 gallons = 
<gadget id="calculator">18480+10500</gadget>
<output>28_980</output>
28,980 gallons.

<result>28_980</result>