The ratio of the present ages of a man and his wife is 7 : 6. Which of the following can't be a possible ratio of their ages 40 years ago?
Choices
A) 5: 7 B) 6: 7 C) 7:7 D) 8: 7 E) 9: 7
7x-40/6x-40 = 8/7   Therefore x=-40   Age cannot be negative.   Answer: 8: 7
<result>D</result>
The ratio of the present ages of a man and his wife is 7 : 6. Which of the following can't be a possible ratio of their ages 40 years ago?