If the average cost of a house was $50,000 in 1955 and was x in 2005, what was the average increase in home prices per year over this period?  Choose the correct choice from the following choices:
A) A)(x+50,000)/40
B) D)(50,000-x)/40
C) C)(50,000/40)+x
D) B)(x-50,000)/50
E) E)x/40
Average house price in 2005: x   Average house price in 1965: 50,000   2005-1955= 
<gadget id="calculator">2005-1955</gadget>
<output>50</output>
50   Average increase per year: (x-50,000)/50   Answer is B)(50,000-x)/40
<result>D</result>
If the average cost of a house was $50,000 in 1955 and was x in 2005, what was the average increase in home prices per year over this period?