On a certain planet where people usually tend to live for more than a century, the ratio of present ages of father and son is 7:4. 10 years later, the ratio of their ages will be 5:3. What is the sum of their present ages?	Answers: A) 220 B) 200 C) 140 D) 80 E) 60
The ratio of present ages of father and son is 7:4, so suppose the present ages are 7x and 4x, respectively.   10 years later, the ages of father and son, respectively, shall be 7x + 10 and 4x + 10.   The ratio of ages 10 years later is given to be 5:3.   This means   (7x + 10)/(4x + 10) = 5/3   Solving we get x = 20.   So present age of father is 7x = 140 and present age of son is 4x = 80.   The sum of present ages is thus 220.   220ns 220
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On a certain planet where people usually tend to live for more than a century, the ratio of present ages of father and son is 7:4. 10 years later, the ratio of their ages will be 5:3. What is the sum of their present ages?