SOLUTION: i'm older than my sister. 15 years ago her age was 1/3 of what my age is now. 10 years ago my age was twice what her age was 15 years ago. what is my age today?

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Question 1100859: i'm older than my sister. 15 years ago her age was 1/3 of what my age is now. 10 years ago my age was twice what her age was 15 years ago. what is my age today?
Found 2 solutions by stanbon, josgarithmetic:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
i'm older than my sister. 15 years ago her age was 1/3 of what my age is now. 10 years ago my age was twice what her age was 15 years ago. what is my age today?
----
Equations::
s-15 = (1/3)m
m-10 = 2(s-15)
------------------------
Rearrange::
3s - 45 = m
2s - 30 = m-10
--------------------
s - 15 = 10
s = 25 yrs (Sister's age now)
----
m = 3s-45 = 30 (my age today)
--------------
Cheers,
Stan H.

Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
y, "my" age
x, sister's age
y%3Ex
-
system%28x-15=%281%2F3%29y%2Cy-10=2%28x-15%29%29

3x-45=y
-
%283x-45%29-10=2x-30
3x-55=2x-30
x=55-30
x=25
-
y=3x-45
y=75-45
highlight%28y=30%29