Question 348158
The problem is Anna is twice as old as her brother Dennis, who is 4 years older 
than their brother Curtis.
 The sum of their ages is 32. How old is Anna?
:
let a = Anna's age
let d = Dennis's age
let c = Curtis's age
:
Write an equation for each statement, we will try to get everything in terms of d:
:
"Anna is twice as old as her brother Dennis"
a = 2d
:
"who is 4 years older than their brother Curtis."
d = c + 4
Subtract 4 from both sides, and we have
c = d-4
:
" The sum of their ages is 32."
a + d + c = 32
:
Replace a with 2d, and replace c with (d-4)
2d + d + (d-4) = 32
2d + d + d = 32 + 4
4d = 36
d = {{{36/4}}}
d = 9 yrs is Denni's age
then
a = 2(9) = 18 is Anna's age