SOLUTION: A father is four times as old as his daughter. In 6 years, he will be three times as old as she is. How old is the daughter now

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Question 648729: A father is four times as old as his daughter. In 6 years, he will be three times as old as she is. How old is the daughter now

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +f+ = the Father's age now
Let +d+ = the Daughter's age now
given:
(1) +f+=+4d+
(2) +f+%2B+6+=+3%2A%28+d+%2B+6+%29+
-----------------------
(2) +f+%2B+6+=+3d+%2B+18+
(2) +f+=+3d+%2B+12+
Substitute (1) into (2)
(2) +4d+=+3d+%2B+12+
(2) +d+=+12+
and, since
(1) +f+=+4d+
(1) +f+=+4%2A12+
(1) +f+=+48+
--------------
The Daughter is 12 now
check:
(2) +f+%2B+6+=+3%2A%28+d+%2B+6+%29+
(2) +f+%2B+6+=+3%2A%28+12+%2B+6+%29+
(2) +f+%2B+6+=+36+%2B+18+
(2) +f+=+54+-+6+
(2) +f+=+48+
OK