SOLUTION: Please help me solve this problem and turn it into equation: Kenny is seven years older than his sister. The sum of their ages is 31. Find the age of each.

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Question 988944: Please help me solve this problem and turn it into equation: Kenny is seven years older than his sister. The sum of their ages is 31. Find the age of each.
Found 2 solutions by macston, josmiceli:
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
.
K=Kenny's age; S=sister's age
.
K=S+7yrs Use this to substitute for K.
.
K+S=31 Substitute for K from above.
S+7+S=31
2S=24
S=12 ANSWER 1: Sister is 12 years old.
.
K=S+7yrs=12yrs+7yrs=19yrs ANSWER 2: Kenny is 19 years old.


Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +k+ = Kenny's age
Let +s+ = his sister's age
given:
(1) +k+=+s+%2B+7+
(2) +k+%2B+s+=+31+
---------------------
Substitute (1) into (2)
(2) +s+%2B+7+%2B+s+=+31+
(2) +2s+=+24+
(2) +s+=+12+
and
(1) +k+=+s+%2B+7+
(1) +k+=+12+%2B+7+
(1) +k+=+19+
------------------
Kenny is 19
His sister is 12
-----------------
check:
(2) +k+%2B+s+=+31+
(2) +19+%2B+12+=+31+
(2) +31+=+31+
OK