SOLUTION: 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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Question 122178: Ricardo is 4 years less than twice as old as his sister. The sum of their ages is 20. How old is Ricardo?
Found 2 solutions by jasonlin00, josmiceli:
Answer by jasonlin00(6) About Me  (Show Source):
You can put this solution on YOUR website!
Ricardo is 12 years old.
(12+4)/2= 8
which is 20 years old in sum

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
r = Ricardo's age
s = sister's age
r+=+2s+-+4
r+%2B+s+=+20
s+=+20+-+r
Substitute this value of s in 1st equation
r+=+2s+-+4
r+=+2%2A%2820+-+r%29+-+4
r+=+40+-+2r+-+4
3r+=+36
r+=+12 answer
check answer
r+%2B+s+=+20
12+%2B+s+=+20
s+=+8
r+=+2s+-+4
12+=+2%2A8+-+4
12+=+16+-+4
12+=+12
OK