The ratio of the present age of Sandy to that of Molly is 7:2. Sixteen years from now, the ratio of the ages of Sandy to Molly will be 5:2. What was Sandy's age 6 years ago?  Choose the correct choice from the following.
A) 66 B) 70 C) 74 D) 78 E) 82

Rationale: let the present age of sandy be 7 x years and that of molly be 2 x years . ( 7 x + 16 ) / ( 2 x + 16 ) = 5 / 2 4 x = 48 x = 12 six years ago , sandy ' s age was 7 ( 12 ) - 6 = 78 the answer is d .
Answer: D