Question 764374
tony is 21 years older than his sister. in 10 years he will be twice as old as his sister. how old is each of them 
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Equations:
t = s + 21
t+10 = 2(s+10)
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Substitute for "t" and solve for "s":
s+21+10 = 2s+20
s + 31 = 2s + 20
s = 11 (sister's age now)
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Solve for "t":
t = s + 21
t = 32 (tony's age now)
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Cheers,
Stan H.
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