2007-03-11 03:58:29 · 11 answers · asked by barbjs45 1 in Science & Mathematics ➔ Mathematics
R = 2S - 4
R + S = 20 ..... S= 20 - R
R = 2(20 - R) - 4
R = 40 - 2R - 4
3R = 36
R = 12
Ricardo is 12 years old (his sister is 8 years old)
2007-03-11 04:03:03 · answer #1 · answered by superguytim 3 · 0⤊ 0⤋
If Richardo is 12, then 12+4=16, which is twice as large as 8. Since 12 + 8 = 20, then your answer is that Richardo is 12 years old.
2007-03-11 04:11:48 · answer #2 · answered by Cameron P 2 · 0⤊ 0⤋
You have R + 4 = 2S
and R + S = 20 where R and S are respectively Ricardo's and his sisters's ages
From this simple set of equations one gets R = 12 and S = 8
2007-03-11 04:05:44 · answer #3 · answered by physicist 4 · 0⤊ 0⤋
Let Ricardo's age be R
Let Sister's age be S
R=(2S-4)
(2S-4) + S = 20
3S-4=20
3S=20+4
S=24/3 = 8
Sister is 8
Ricardo is (8x2)-4 = 16-4 = 12
to check : 8+12=20
2007-03-11 04:06:56 · answer #4 · answered by TAGG 2 · 1⤊ 0⤋
Let sister's age = x
Let Ricardo's age = 2x - 4
x + 2x - 4 = 20
3x - 4 = 20 (Add 4 to both sides)
3x = 24 (Divide both sides by 3)
x = 8
Sister's age = 8
Ricardo's age = 2(8) - 4 = 12
QED
2007-03-11 04:43:10 · answer #5 · answered by CSUFGrad2006 5 · 0⤊ 0⤋
Ricardo is 12 years old!!
(while his sister is 8 years old. Since he is 2x as old minus 4 years)
Ricardo =x
His sister= y
x+y=20 where (Ricardo) x=2y-4 then,
2y-4+y=20
3y=24
y=8
2007-03-11 04:11:50 · answer #6 · answered by neurogirl103 4 · 0⤊ 0⤋
Is ricardo 12?
2007-03-11 04:03:27 · answer #7 · answered by surfer1 3 · 0⤊ 0⤋
Ricardo is 12, which menas his sister is obviously 8.
2007-03-11 04:27:45 · answer #8 · answered by hokieman3000 2 · 0⤊ 0⤋
r = (2 * sis)-4
so
sis + r = 20
sis + (2*sis) - 4 = 20
sis + 2sis = 24
3sis=24
sis = 8
so Ricardo = 12
2007-03-11 04:03:01 · answer #9 · answered by hey mickey you're so fine 3 · 0⤊ 0⤋
12.
2007-03-11 04:01:40 · answer #10 · answered by T M 2 · 0⤊ 0⤋