SOLUTION: the sum of brads age and his fathers age is 58. in four years brads father will be twice as old as brad what are their ages now?

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Question 552775: the sum of brads age and his fathers age is 58. in four years brads father will be twice as old as brad what are their ages now?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +b+ = Brad's age now
Let +f+ = Father's age now
+b+%2B+4+ = Brad's age in 4 years
+f+%2B+4+ = Father's age in 4 years
--------------------------
given:
(1) +b+%2B+f+=+58+
(2) +f+%2B+4+=+2%2A%28+b+%2B+4+%29+
------------------
(1) +b+=+58+-+f+
Substitute (1) into (2)
(2) +f+%2B+4+=+2%2A%28+58+-+f+%2B+4+%29+
(2) +f+%2B+4+=+116+-+2f+%2B+8+
(2) +3f+=+116+%2B+8+-+4+
(2) +3f+=+120+
(2) +f+=+40+
and, since
(1) +b+%2B+f+=+58+
(1) +b+%2B+40+=+58+
(1) +b+=+18+
Brad is 18 and Father is 40
check answer:
(2) +f+%2B+4+=+2%2A%28+b+%2B+4+%29+
(2) +40+%2B+4+=+2%2A%28+18+%2B+4+%29+
(2) +44+=+2%2A22+
(2) +44+=+44+
OK