MathDB
Isabella's Vacation

Source:

January 5, 2009

Problem Statement

On a trip from the United States to Canada, Isabella took d d U.S. dollars. At the border she exchanged them all, receiving 10 10 Canadian dollars for every 7 7 U.S. dollars. After spending 60 60 Canadian dollars, she had d d Canadian dollars left. What is the sum of the digits of d d? <spanclass=latexbold>(A)</span> 5<spanclass=latexbold>(B)</span> 6<spanclass=latexbold>(C)</span> 7<spanclass=latexbold>(D)</span> 8<spanclass=latexbold>(E)</span> 9 <span class='latex-bold'>(A)</span>\ 5\qquad <span class='latex-bold'>(B)</span>\ 6\qquad <span class='latex-bold'>(C)</span>\ 7\qquad <span class='latex-bold'>(D)</span>\ 8\qquad <span class='latex-bold'>(E)</span>\ 9