Sandy is younger than Molly by 20 years. If the ratio of their ages is 7:9, how old is Sandy?
Choose the correct option
A) 42  B) 49  C) 56  D) 63  E) 70
Let Sandy's age be 7x and let Molly's age be 9x.   9x - 7x = 20   x = 10   Sandy is 70 years old.   The answer is 70.
<result>E</result>
Sandy is younger than Molly by 20 years. If the ratio of their ages is 7:9, how old is Sandy?