Question 61363
Ricardo is 4 years less than twice as old as his sister.  The sum of their ages is 20.  How old is Ricardo?
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Let sister's age be "x".
Then Ricardo's age is "2x-4"
EQUATION:
sum of their ages is 20
x+2x-4=20
3x=24
x=8 (sister's age)
2x-4=12 (Ricardo's age)
Cheers,
Stan H.