Joe is 5 years older than Sally. In 15 years Joe will be 3 times as old as Sally is now. How old is Sally now? Hint: Write Joe's age now in terms of Sally's age now. Then write Joe's age in 15 years using the expression you just wrote for Joe's age now. Then using S for Sally's age now, write the equation in only one variable "S" and solve it.
2006-08-15 06:16:30 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
j = s + 5
j + 15 = 3s
j + 15 = 3(j - 5)
30 = 2j
j (present) = 15
s (present) = 10
j (future) = 30
2006-08-15 06:22:05 · answer #1 · answered by shmifty__14 5 · 0⤊ 1⤋
J = 5 + S
J + 15 = 3 S
__________________
Subbing 1 into 2
(5+S) + 15 = 3S
20 + S = 3S
20 = 2S
S = 10
So now sally is 10 and joe is 15.
In 15 years Joe will be 30 ( 3 times 10- sallys current age) and coincidentally Sally will be 25... legal for Joe now
2006-08-15 13:23:34 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Joe = S + 5
Joe + 15 = 3S
Joe + 15 = S + 20 = 3S
2S = 20, so Sally is 10 now and Joe is 15.
2006-08-15 13:22:49 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Sally is 10
2006-08-15 13:48:42 · answer #4 · answered by Carlitos 3 · 0⤊ 0⤋
j=s+5
j+15=3s
(s+5)+15=3s
s+20=3s
20=2s
s=10
sally= 10
joe=15
2006-08-15 13:35:38 · answer #5 · answered by Carpe Diem (Seize The Day) 6 · 0⤊ 0⤋
Sally is 10.
Why am I doing your homework?
2006-08-15 13:22:26 · answer #6 · answered by Jaq 2 · 0⤊ 1⤋
J=S+5
J+15=3S
Combining...
(S+5)+15=3S
S+20=3S
2S=20
S=10
Sally is 10 years old now.
2006-08-15 13:27:47 · answer #7 · answered by stellarfirefly 3 · 0⤊ 0⤋
j = s+5
j+15 = 3s
So, s+5+15 = 3s
or 2s = 20
or s=10
If you have to get your homework done don't make it so obvious by giving the accompanying hint too.
2006-08-15 13:36:47 · answer #8 · answered by ag_iitkgp 7 · 0⤊ 0⤋