Question 1188727
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The difference between their ages is 73-5=68 years.<br>
When the grandfather is 5 times as old as his grandson -- i.e., 4 times OLDER THAN -- the grandson's age will be 68/4=17 and the grandfather's age will be 17*5=85.<br>
Since their current ages are 5 and 73, that will be 12 years from now.<br>