SOLUTION: Jose is old as Edwin will be when Jose is twice as old as Edwin was when Jose's age was half the sum of their present ages. Edwin is as old as Jose was when Edwin was half the age

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Question 1133494: Jose is old as Edwin will be when Jose is twice as old as Edwin was when Jose's age was half the sum of their present ages. Edwin is as old as Jose was when Edwin was half the age he will be ten years from now. How old is Jose?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = Jose's age now
Let +b+ = Edwin's age now
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For some reason, I like to this particular type
of problem from the end to the beginning.
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" when Edwin was half the age he will be ten years from now."
In +10+ yrs, Edwin will be +b+%2B+10+
Half of that is +%28+b+%2B+10+%29%2F2+
-------------------------------------
" Edwin is as old as Jose was . . ."
I'll assume that Jose' is the older one
(1) +b+=+%28+b+%2B+10+%29%2F2+%2B+%28+a+-+b+%29+
I put in the +a+-+b+ because the difference in their ages
never changes
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" when Jose's age was half the sum of their present ages. "
+%28+a+%2B+b+%29%2F2+
--------------------------------------
" when Jose is twice as old as Edwin was. . . "
Edwin was:
+%28+a+%2B+b+%29%2F2+-+%28+a+-+b+%29+
" when Jose is "
+2%2A%28+%28+a+%2B+b+%29%2F2+-+%28+a+-+b+%29+%29+
--------------------------------------
" Jose is old as Edwin will be . . "
(2) +a+=+2%2A%28+%28+a%2B+b+%29%2F+2+-+%28+a+-+b+%29+%29+-+%28+a+-+b+%29+
-----------------------------------------------
I have 2 equations with 2 unknowns, so it's solvable
(2) +a+=+a+%2B+b+-+2%2A%28+a+-+b+%29+-+%28+a+-+b+%29+
(2) +a+=+a+%2B+b+-+2a+%2B+2b+-+a+%2B+b+
(2) +a+=+4b+-+2a+
(2) +3a+=+4b+
(2) +b+=+%283%2F4%29%2Aa+
and
(1) +b+=+%28+b+%2B+10+%29%2F2+%2B+%28+a+-+b+%29+
(1) +2b+=+b+%2B+10+%2B+2%2A%28+a+-+b+%29+
(1) +2b+=+b+%2B+10+%2B+2a+-+2b+
(1) +2b+=+2a+-+b+%2B+10+
(1) +3b+=+2a+%2B+10+
Substitute (2) into (1)
(1) +3%2A%283%2F4%29%2Aa+=+2a+%2B+10+
(1) +9a+=+8a+%2B+40+
(1) +a+=+40+
Jose' is 40 yrs old
------------------------------
check:
(2) +b+=+%283%2F4%29%2Aa+
(2) +b+=+%283%2F4%29%2A40+
(2) +b+=+30+
" when Edwin was half the age he will be ten years from now."
Edwin was +%28+30+%2B+10+%29%2F2+=+20+ yrs old
--------------------------------------------
" Edwin is as old as Jose was . . ."
(1) +b+=+%28+b+%2B+10+%29%2F2+%2B+%28+a+-+b+%29+
(1) +30+=+20+%2B+%28+40+-+30+%29+
(1) +30+=+20+%2B+10+
------------------------------
" when Jose's age was half the sum of their present ages. "
+%28+40+%2B+30+%29%2F2+=+35+
-----------------------------
" when Jose is twice as old as Edwin was. . . "
Edwin was:
+%28+a+%2B+b+%29%2F2+-+%28+a+-+b+%29+
+35+-+%28+40+-+30+%29+=+25+
----------------------------
" when Jose is "
+2%2A%28+%28+a+%2B+b+%29%2F2+-+%28+a+-+b+%29+%29+
+2%2A25+=+50+
-------------------------------
" Jose is old as Edwin will be . . "
(2) +a+=+2%2A%28+%28+a%2B+b+%29%2F+2+-+%28+a+-+b+%29+%29+-+%28+a+-+b+%29+
(2) +40+=+50+-+%28+40+-+30+%29+
(2) +40+=+50+-+10+
OK
Seems to check out. Get another opinion if needed