Question 63481: Ricardo is 4 years less than twice as old as his sister. The sum of their ages is 20. How old is Ricardo? Answer by joyofmath(189) (Show Source):
You can put this solution on YOUR website! Ricardo is 4 years less than twice as old as his sister. The sum of their ages is 20. How old is Ricardo?
Let R = Ricardo's age.
Let S = Sister's age.
Then, R=2*S-4
Also, R+S=20, or R=20-S.
Replacing R in the first equation with 20-S gives us 20-S=2*S-4
Add 4 to both sides: 24-S=2*S
Add S to both sides: 24=3*S, so .
And, since R+S=20 and S=8, .
Let's verify the solution. If the sister is 8 then twice her age minus 4 = 12 which is Ricardo's age.
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