Question

Please help!
Alfonso is 8 years older than Ashley. Five years ago Alfonso was three times as old as Ashley. How old is Ashley now?
So to solve this problem, I substituted Ashley for X and Alfonso for Y. I converted the word problem into 2 equations:
y = x + 8
y -5 = 3x -5
Then I converted the first equation for x:
x = 8 -y
Then I solved for x...but something isn't right.

Answer 1

I set x = Alfanzo and y = Ashley

x = y + 8
x - 5 = 3y

Then I used substitution to solve the set:

Answer 2

I substituted the value of x from the first equation (y+8) into x in the second equation and simplified.

Answer 3

x - 5 = 3y
(y + 8) - 5 = 3y

y + 3 = 3y
-y -y
----------
3 = 2y


3 2y
- = --
2 2

3/2 = y

Answer 4

oh ok! that makes sense. then y = 1.5

Answer 5

Yes! :)

Answer 6

I know that the ages are 9 and 17 now, will try and show how.

Answer 7

although...my textbook says that 1.5 is not the answer. It's higher: either 9, 17, or 8

Answer 8

hmm. okay, may radar can show how... to get right answer from textbook :)

Answer 9

well thank you for coming over and making an effort =) @strawberry17

Answer 10

ur welcome! :)

Answer 11

I am letting x = the age of the older one.Now
then x - 8 = age of the youngest Now
5 years ago then
x-5 is the older one 5 years ago.
x-8-5 is the youngest one 5 years ago (x-13)
we are told that the older one is now 3 times as old as the younger one
(x-5) = 3(x-13)
x-5 =3x -39
x-3x = -39 + 5
-2x= -34
x = 17 older one
x-8=17 - 8 = 9 younger one

Answer 12

Now using the convention you used: Alfonso is the older one so letting x = Alfonsos age now. The letting y = Ashley
y= x - 8 or x = y + 8
Does that agree with your thinking?

Answer 13

Now 5 years earlier: y -5 = 3(x-8-5)
y-5 = 3x - 39. So far so good??

Answer 14

yes but the younger one is x -5 so wouldn't that be:
17 -5?

Answer 15

wait never mind...i looked back it's not like that

Answer 16

No the older one is 17 and 17-5=12 is age of the olderr one 5yrs ago.

Answer 17

the younger one would then be 9 - 5 or only 4 yrs old.

Answer 18

ooooh ok. then the younger one is 9, the older one is 17

Answer 19

thank you

Answer 20

Yes, and I was going to attemp using your convention to solve it you using two unknowns x and y.

Answer 21

But if you understand the way I worked it using only one variable x. I will leave.

Answer 22

hhhhm? i don't understand...what you're wanting to do?

Answer 23

you mean solve for y?

Answer 24

I am at the point 5 years ago where
y-5 = 3x -39

Answer 25

ok. I wanted to find out "what age is Ashley now" so now that I've got that I'm done. but thanks for offering and thank you for helping me out =)

Answer 26

O.K. You're method was legitimate, but somewhere you went awry and I was trying to see where.