David is three times as old as Susan was when David was as old as Susan is now. Susan is now 16. How old is David now?
Hint: The difference between their ages is always the same.
2006-08-19 16:55:40 · 6 answers · asked by Jerry M 3 in Science & Mathematics ➔ Mathematics
24
Say david is x years older than susan.
so david is 16+x now, or d = 16+x
david was as old as susan is now(16) x years ago.
so d = 3(16-x)
so 16+x = 48 - 3x
4x = 32
x = 8
d = 24
2006-08-19 17:39:05 · answer #1 · answered by Scott R 6 · 0⤊ 1⤋
Here's the set up:
Look at the part "when David was as old as Susan is now". This just means "when David was 16".
Dt = Age David then =16
Dn = Age David now
St = Age Susan then
Sn= AgeSusan now =16
David is three times as Susan was, so
Dn = 3St
Let's use the hint. The difference between their ages is always the same, then and now. So,
Dt - St = Dn - Sn is the same as
16 - St = 3St - 16
+16 +16
32- St = 3St
+St +St
32 = 4St
8 = St
Since, Dn = 3St, we have Dn = 3*8 = 24.
2006-08-20 23:07:38 · answer #2 · answered by kim t 3 · 0⤊ 0⤋
David is now 24. He is eight years older than Susan.
When David was 16, Susan was 8. David is now 3X8 =24.
2006-08-20 00:40:28 · answer #3 · answered by q_midori 4 · 0⤊ 1⤋
When DAvid was 16, Susan was 5.33 (16/3).
So, 10.666 years later, Susan is 16 and DAvid is 26.
yeah, seems a bit off....but it's how the math works out for me.
2006-08-20 00:02:34 · answer #4 · answered by Marvinator 7 · 0⤊ 2⤋
16/3=5 1/3
16-5 1/3= 10 2/3
16+10 2/3=26 2/3 years old.
2006-08-20 00:33:44 · answer #5 · answered by Archangel 4 · 0⤊ 2⤋
48
because
16*3=48 and the diffrenceof their age is 32
2006-08-20 00:03:07 · answer #6 · answered by _heart me♥ 1 · 0⤊ 2⤋