SOLUTION: my brother is half as old as i am. my sister is twice as old as i am. the sum of our ages is 35. how old am i?

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Question 1091284: my brother is half as old as i am. my sister is twice as old as i am. the sum of our ages is 35. how old am i?
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
p, person
x, sister
y, brother

system%28y=p%2F2%2Cx=2p%2Cp%2Bx%2By=35%29

Solve for p.

simple substitution,
p%2B2p%2Bp%2F2=35
Solve.

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

my brother is half as old as i am. my sister is twice as old as i am. the sum of our ages is 35. how old am i? 
Let my age be M

Then my brother's age is: matrix%281%2C5%2C+%281%2F2%29%2C+of%2C+%22M%2C%22%2C+or%2C+M%2F2%29 

Sister's age: 2M

We then get: matrix%281%2C3%2C+M+%2B+M%2F2+%2B+2M+=+35%2C+%22=======%3E%22%2C+3M+%2B+M%2F2+=+35%29

6M + M = 70 ------ Multiplying by LCD, 2

7M = 70

M, or my age = highlight_green%28matrix%281%2C3%2C+70%2F7%2C+%22=%22%2C+10%29%29