SOLUTION: The sum of Jamie's age and Devon's age is 30. Ten years ago the product of their ages was 24. If Jamie is younger than Devon, what are their ages?

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Question 58381: The sum of Jamie's age and Devon's age is 30. Ten years ago the product of their ages was 24. If Jamie is younger than Devon, what are their ages?
Found 2 solutions by Edwin McCravy, josmiceli:
Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
The sum of Jamie's age and Devon's age is 30. 
Ten years ago the product of their ages was 24. 
If Jamie is younger than Devon, what are their ages? 


J + D = 30
(J-10)(D-10) = 24

Solve that by substitution. That is

1. Solve the first equation for either letter.
2. Substitute the expression obtained for that letter 
   in the 2nd equation.
3. Solve the resulting equation for the remaining letter.
4. Substitute that in the equation obtained in step 1.
5. Solve for the other letter.

There are two solutions: (D,J) = (14,16), (D,J) = (16,14)
Since we are told that Jamie is younger, we discard the 
first. So the answer is Jamie is 14 and Devon is 16.

Checking:  The sum of their ages is 14+16 or 30.
Ten years ago, Jamie was 4 and Devon was 6, and 4×6 = 24.

Edwin


Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
d = Devon's age
j = Jamies age
j+%2B+d+=+30
%28j+-+10%29%28d+-+10%29+=+24
jd+-10d+-10j+%2B+100+=+24
j%2830+-+j%29+-+10%2830+-+j%29+-+10j+%2B+76+=+0
30j+-+j%5E2+-+300+%2B+10j+-+10j+%2B+76+=+0
-j%5E2+%2B+30j+-+224+=+0
use the formula
j+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
j+=+%28-30+%2B-+sqrt%28+30%5E2-4%2A%28-1%29%2A%28-224%29+%29%29%2F%282%2A%28-1%29%29+
j+=+%28-30+%2B-+sqrt%28+900+-+896+%29%29%2F+-2+
j+=+%28-30+%2B-+sqrt%28+4+%29%29%2F+-2+
j+=+%28-30+%2B-+2%29%2F+-2+
j+=+15+%2B-+1
j = 16,14
j+%2B+d+=+30
if j = 16, then d = 14
if j = 14, then d = 16
The problem said Jamie was younger than Devon, so
Jamie is 14 and Devon is 16