SOLUTION: J.t is 5 years older than twice his sisters age. the sum is 20. how old r they????

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Question 615921: J.t is 5 years older than twice his sisters age. the sum is 20. how old r they????
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +j+ = jt's age
Let +s+ = sister's age
given:
(1) +s+%2B+j+=+20+
(2) +j+=+2s+%2B+5+
---------------
(1) +s+%2B+j+=+20+
(2) +2s+-+j+=+-5+
Add the equations
+3s+=+15+
+s+=+5+
and, since
(1) +s+%2B+j+=+20+
(1) +5+%2B+j+=+20+
(1) +j+=+15+
JT is 15 and his sister is 5