Problema Solution
when jane was twice as old as linda is now linda was one third as old as jane is now seven years ago linda was four times as old as jane is now what are their ages
Answer provided by our tutors
You can put this solution on YOUR website!
jane is 27
linda is 12
here's how:
let x = jane's age now.
let y = linda's age now.
7 years ago, jane was 4 times linda's age.
equation for that is:
x-7 = 4*(y-7)
simplify to get:
x-7 = 4y-28
solve for x to get:
x = 4y-21
when jane was 2 times linda's age, linda was 1/3 * jane's age.
this happened k years ago (we use letter k because we don't know how many years ago at this point in time).
equation for this is:
x-k = 2y
y-k = x/3
solve both these equations for k to get:
k = x-2y
k = y-x/3
since both equations are equal to k, you can set the expressions on the right of each equation equal to each other to get:
x-2y = y-x/3
multiply both sides of this equation by 3 to get:
3x-6y = 3y-x
add 6y to both sides of this equation and add x to both sides of this equation to get:
4x = 9y
divide both sides of this equation by 4 to get:
x = 9y/4
you now have 2 equations for x.
you have:
x = 4y-21
x = 9y/4
since both equations are equal to x, you can set the expressions on the right of each equation equal to each other to get:
4y-21 = 9y/4
multiply both sides of this equation by 4 to get:
16y-84 = 9y
subtract 9y from both sides of this equation and add 84 to both sides of this equation to get:
7y = 84
divide both sides of this equation by 7 to get:
y = 12
you should be able to use any of the equations to solve for x to get x = 27.
the one i used was the original one of:
x = 4y-21
this yielded x = 27
x = 9y/4 yielded x = 27 also.
you have x = 27 and y = 12
that's your answer.
to confirm, do the following from the original problem statement of:
when i was twice as old as you are now said Jane you were a third as old as i am now. Linda thought for a moment thats right she agreed and seven years ago you were 4 times as old as i was.
jane is 27
linda is 12.
7 years ago jane was 20 and linda was 5 which made jane 4 times as old as linda.
jane was twice as old as linda is now when jane was 24.
that was 3 years ago.
3 years ago, linda was 9 and and jane was 24 which made linda 1/3 as old as jane.
all portions of the problem statement check out so the answer is good.
CORRECTION TO PREVIOUS STATEMENT
3 years ago jane was 24 which is 2 times as old as linda is now (12).
3 years ago linda was 9 which is 1/3 times as old as jane is now (27).
answer is correct but last statement might have been confusing and so was corrected.