0
Four years ago Jane was twice as old as Sam. Four years from now Sam will be three-fourths of Jane's age. How old is Jane now?
Wiki User
∙ 10y ago
4 years ago Jane was 8, Sam was 4. In 4 years from now, Jane will be 16 and Sam will be 12.
So Jane is 12 years old now.
Let's turn this into an algebra problem
We'll use J for Jane's age now, and S for Sam's age now, and make an equation which shows the relationship four years ago.
J - 4 = 2(S - 4) and we'll work out the brackets and move the unknowns to the same side
J - 4 = 2S - 8
J - 2S = - 8 + 4
J - 2S = - 4
Now we'll do another equation to show the relationship in four years time
3/4(J + 4) = S + 4 --- and we'll multiply both sides by 4 to get rid of that fraction
3(J + 4) = 4(S + 4)
3J + 12 = 4S + 16
3J - 4S = 16 - 12
3J - 4S = 4
Now we need to make one of the unknown the same value so we can subtract the two equations.... if we multiply the top one by -3 we get
-3J +6S = 12, and if we add that to the second equation we will get a new equation with no J value
3J - 4S = 4
-3J +6S = 12
----------------
0J + 2S = 16
Therefore S = 8, and we can now substitute 8 for S in any of the other equations, and check the answer we get for J
J - 2(8) = - 4
J - 16 = - 4
J = - 4 + 16
J = 12
Now, if we are right then substituting these values not the second equation should give a correct sum.
3J - 4S = 4
3(12) - 4(8) = 4
36 - 32 = 4
Which is correct,.... so we know that the calculations are right.
To put that whole puzzle into real number then we look at he first statement
Four years ago Jane (who was then 12-4) was 8. The was twice as old as Sam (who was then 8 - 4) who was 4.
Four years from now Sam (will be 8 + 4) at 12, will be three-quarters of Jane's (who will be 12 + 4) age of 16. Correct answer is 12.
Wiki User
∙ 10y ago
Add your answer:
Earn +20 pts
Jamar is four times as old as josh In twice years he will be twice as old as Josh How old is Jamar?
Jamar is four times as old as Josh. In 20 years he will be twice as old as Josh. How old is Jamar?
Frank is 15 years younger then John. In 5 years John will be twice as old as Frank. How old will Frank be in four years?
In four years.. Frank will be 14.
Jamar is four times as old as josh In 20 years he will be twice as old as josh how old is Jamar?
Jamar is four times as old as Josh. In 20 years he will be twice as old as Josh. How old is Jamar?
Can the president be elected to a six year term of office?
No, four years, twice is the maximum.
Helen is thirteen years old. Helen's father is four years more than twice her age?
4+(2X13)
Your father is four times as old as you are In 20 years he will only be twice as old as you are How old are you now?
You are 10 years old
Raju is 15 years younger then Baiju In 5 years Baiju will be twice as old as Raju How old will Raju be in four years?
12
Jamar is four times as old as Josh. In 20 years he will be twice as old as Josh. How old is Jamar?
He is 40 years old.
What happens once in a second twice in a minute four times in a hour but never in a million years?
a heartbeat!!
abdella is 15 years younger than ayele . in 5 years ayele will be twice as old as abdella how old will abdella be in four years pdf?
35
John is twice as old as his brother Four years ago he was four times as old as his brother Find their present ages?
The ages are 8 and 4
Stefanie is twice as old as Amber In four years the sum of Stefanie and Amber will be 20 How old is Amber?
4
