On a ferry, there are 20 cars and 10 trucks. The cars have an average mass of 1200 kg and the trucks have an average mass of 3000 kg. What is the average mass of all 30 vehicles on the ferry?  Options:	A) 1800	B) 1900	C) 2000	D) 2100	E) 2200
The total mass of the vehicles is 20*1200+10*3000= 
<gadget id="calculator">20*1200+10*3000</gadget>
<output>54_000</output>
54000   The average mass is   54000/30= 
<gadget id="calculator">  54000/30</gadget>
<output>1_800</output>
1800.   The answer is 1800.
<result>A</result>
On a ferry, there are 20 cars and 10 trucks. The cars have an average mass of 1200 kg and the trucks have an average mass of 3000 kg. What is the average mass of all 30 vehicles on the ferry?