Question

sarah is twice as old as john. six years ao, sarah was 4 times as old as john was then. how old is john now?

Answer 1

First step in algebraic word problems is to represent values :)
If we let x be the age of John now, what is the age of Sarah?

Answer 2

2x?

Answer 3

Good :)
Okay, so what would be John's age SIX YEARS AGO ?

Answer 4

2x-6? :)

Answer 5

uh-uh, that's ROSE's age six years ago. What about John?

Answer 6

Remember, John's age now is x.

Answer 7

omg fail

Answer 8

um well idk

Answer 9

forget I said anything... that's Sarah

Answer 10

Sarah's age 6 years ago was 2x - 6

Answer 11

lol XD i was so confused

Answer 12

Sorry, rosie, I was putting you in the problem XD

Answer 13

lol

Answer 14

gah

Answer 15

But anyway, John's age now is x,
Sarah's age now is 2x.
Six years ago, their ages should be...?

Answer 16

so sarahs age is six yrs ago was 2x-6

Answer 17

yup. What about John?

Answer 18

and john is 4x-6?

Answer 19

No...
John's age now is x.
so six years ago, it should be...? (if you're 20 now, six years ago it would be 14...)

Answer 20

x-6?

Answer 21

Yes, precisely :D

Answer 22

John's age six years ago = x - 6
Sarah's age six years ago = 2x - 6

Now, to quote your problem:
Six years ago, Sarah was 4 times as old as John was then.

How do you translate that in math terms?

Answer 23

4(2x-6)(x-6)?

Answer 24

or is it 4(x-6)

Answer 25

Okay, I'll translate, you solve... :)
Trust me, the only difficult thing in these word problems is finding what problem to solve... when you get it, it's usually easy :)
Now...
Six years ago...
(this only means we'll be using their ages six years ago)

Sarah
2x - 6

was
2x - 6 =

4 times
2x - 6 = 4()

as old as John was then
2x - 6 = 4(x - 6)

Now just solve for x... which we know to be John's age now :D

Answer 26

oh my god thank you so much. this is from the book for the sats. i was studying so yea :)

Answer 27

Thank me by telling me your answer :3

Answer 28

ok so i got 9. is that correct?

Answer 29

Bingo :)

Answer 30

yay finally got it. thanks so much :)

Answer 31

No problem :)