2007-11-21 02:31:58 · 5 answers · asked by crocsroc 2 in Science & Mathematics ➔ Mathematics
can you show the work?
2007-11-21 02:37:46 · update #1
Let's say that Bill's age now is B, and Juan's age now is J.
If Bill is twice as old as Juan, that means, for example, if Juan is 12, then Bill is 24. If Juan is 39, then Bill is 78, and so on. But since we don't know either person's age, we'll just use our unknown variables, so
2B = J.
Also, the sum of their ages three years ago was 45. So.. for example, if Juan is 12, and Bill is 24, then three years ago, Juan was 9, Bill was 21, and the sum was 30. In other words, we did (12-3) + (24-3), or, in terms of variables, since we still don't know anyone's age yet,
(B-3) + (J-3) = 45.
Now we have these two equations and two unknowns:
2B = J
(B-3) + (J-3) = 45.
simplify and substitute:
2B = J
B + J - 6 = 45
B + J = 51
B + 2B = 51
3B = 51
so B = 17, and J = 2B = 34.
Bill is 17 and Juan is 34.
2007-11-21 02:42:34 · answer #1 · answered by bloopbloop 2 · 3⤊ 0⤋
"Bill is twice as old as Juan"
B = 2*J
"their ages three years ago"
(B-3) and (J-3)
"The sum of their ages three years ago was 45"
(B-3) + (J-3) = 45
B + J = 51
"How old are they now?"
Since B = 2*J and B + J = 51:
B + J = 2J + J
51 = 3J
Solve for J, then mult by 2 to get B
2007-11-21 02:39:29 · answer #2 · answered by DWRead 7 · 2⤊ 0⤋
Bill is 32 and Juan is 16.
2007-11-21 02:36:38 · answer #3 · answered by Tracy W 2 · 0⤊ 2⤋
bill is 34
juan is 17
34-3 = 31
17-3 = 14
31+14=45
2007-11-21 02:39:17 · answer #4 · answered by wag1 2 · 1⤊ 1⤋
Bill=2x
Juan =x
2x+x=45+3
3x=48
x=16
2x=32
Juan is 16 Bill is 32
2007-11-21 02:38:47 · answer #5 · answered by Dave aka Spider Monkey 7 · 0⤊ 2⤋