SOLUTION: Mrs Thompson has a son and daughter. She is twice as old as her son and her son is twice as old as her daughter. The total of their ages is 91 years. How old is her son?

Algebra ->  Equations -> SOLUTION: Mrs Thompson has a son and daughter. She is twice as old as her son and her son is twice as old as her daughter. The total of their ages is 91 years. How old is her son?      Log On


   

Question 1092453: Mrs Thompson has a son and daughter. She is twice as old as her son and her son is twice as old as her daughter. The total of their ages is 91 years. How old is her son?
Found 3 solutions by josgarithmetic, ikleyn, MathTherapy:
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
m, s, d
Mother, Son, Daughter
system%28m=2s%2Cs=2d%2Cm%2Bs%2Bd=91%29

.
.
.

system%28d=13%2Cs=26%2Cm=52%29, the son is 26 years.

Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.
Let x be the daughter's age, in years.


Then her brother's age is 2x years.


Then Mrs Thompson age is 4x years.


The condition says that   x + 2x + 4x = 91,   or   7x = 91.


=============> x = 91/7 = 13.


Answer.  Her son is 26 years old.


Answer by MathTherapy(10551) About Me  (Show Source):
You can put this solution on YOUR website!

Mrs Thompson has a son and daughter. She is twice as old as her son and her son is twice as old as her daughter. The total of their ages is 91 years. How old is her son?
Let son's age be S

Then mother's is 2S, and daughter's is matrix%281%2C3%2C+%281%2F2%29S%2C+or%2C+S%2F2%29

We then get: 

6S + S = 182 ------ Multiplying by LCD, 2  

7S = 182

S, or son is: highlight_green%28matrix%281%2C4%2C+182%2F7%2C+%22=%22%2C+26%2C+%22years-old%22%29%29