The ratio between the present ages of A and B is 7:3 respectively. The ratio between A's age 4 years ago and B's age 4 years hence is 1:1. What is the ratio between A's age 4 years hence and B's age 4 years ago?
Choose the correct choice:
A) 3:4  B) 3:0  C) 9:1  D) 9:2  E) 3:9
Let the present ages of A and B be 7x and 3x years respectively.   Then, (7x - 4)/(3x + 4) = 1/1   4x = 8 =&gt; x = 2   Required ratio = (5x + 4):(3x - 4) = 18:2 = 9:1.Answer: 9:1
<result>C</result>
The ratio between the present ages of A and B is 7:3 respectively. The ratio between A's age 4 years ago and B's age 4 years hence is 1:1. What is the ratio between A's age 4 years hence and B's age 4 years ago?