SOLUTION: Mary Beth's age is 3 times the age of her sister Ellen. Ellen is now 4 years old. How old will they both be whe Mary Beth is only twice the age of Ellen?

Algebra ->  Customizable Word Problem Solvers  -> Age -> SOLUTION: Mary Beth's age is 3 times the age of her sister Ellen. Ellen is now 4 years old. How old will they both be whe Mary Beth is only twice the age of Ellen?      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 767663: Mary Beth's age is 3 times the age of her sister Ellen. Ellen is now 4 years old. How old will they both be whe Mary Beth is only twice the age of Ellen?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +m+ = Mary Beth's age now
Let +e+ = Ellen's age now
+e+=+4+
+m+=+3e+
+m+=+12+
------------
Let +n+ = number of years from now when
Mary Beth is twice Ellen's age
+m+%2B+n+=+2%2A%28+e+%2B+n+%29+
+12+%2B+n+=+2%2A%28+4+%2B+n+%29+
+12+%2B+n+=+8+%2B+2n+
+n+=+12+-+8+
+n+=+4+
In 4 years, Mary Beth will be twice Ellen's age
check:
+12+%2B+4+=+16+
+4+%2B+4+=+8+
16 is twice 8
OK