Question 895240: Hi,
My math teacher (at school) and I have a conflict on the following specific problems. I would appreciate if you can provide your input on this. We just need to identify the equations in each case:
Let Bob's age (in years) now = B
Let his Sister's age (in years) now = S
Let his Brother's age (in years) now = R
Problem 1: In three years, Bob will be five years older than his sister will be. How old is his sister?
S = ?
Problem 2: In three years, Bob will be twice as old as his brother will be. How old is his brother?
R = ?
Found 2 solutions by Alan3354, MathTherapy:
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! Let Bob's age (in years) now = B
Let his Sister's age (in years) now = S
Let his Brother's age (in years) now = R
Problem 1: In three years, Bob will be five years older than his sister will be. How old is his sister?
B + 3 = 5*(S + 3) = 5S + 15
5S = B - 12
S = (B - 12)/5
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Problem 2: In three years, Bob will be twice as old as his brother will be. How old is his brother?
B + 3 = 2*(R + 3) = 2R + 6
2R = B - 3
R = (B - 3)/2
Answer by MathTherapy(10557)  (Show Source):
You can put this solution on YOUR website! Hi,
My math teacher (at school) and I have a conflict on the following specific problems. I would appreciate if you can provide your input on this. We just need to identify the equations in each case:
Let Bob's age (in years) now = B
Let his Sister's age (in years) now = S
Let his Brother's age (in years) now = R
Problem 1: In three years, Bob will be five years older than his sister will be. How old is his sister?
S = ?
Problem 2: In three years, Bob will be twice as old as his brother will be. How old is his brother?
R = ?
Problem 1
B = S + 5_____S = B – 5.
It doesn’t matter which year we're talking about. Starting from his sister's birth year, Bob was 5 years
older than her, so his age will ALWAYS be S + 5, and her age will ALWAYS BE represented by: 
Problem 2:
B + 3 = 2(R + 3)
B + 3 = 2R + 6
B + 3 – 6 = 2R
B – 3 = 2R
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