Question 1144239: David Is 6 years older than his sister Delia. In 10 years the sum of There age 52. how old are David and Delia
today Found 2 solutions by ikleyn, greenestamps:Answer by ikleyn(52786) (Show Source):
If David is x years old, then Delia is (x-6) years old.
In 10 years David will be (x+10) years old; Delia will be ((x-6)+10) = (x+4) years old.
The condition says
(x+10) + (x+4) = 52.
It implies
2x + 14 = 52,
2x = 52 - 14 = 38
x = 38/2 = 19.
ANSWER. David's age is 19 years. Delia is 19-6 = 13 years old.
Something like this, if you want/need to use formal algebra....
L = Delia now
L+6 = David now
L+10 + Delia 10 years from now
L+16 = David 10 years from now
(L+10)+(L+16) = 52
Solve using basic algebra.
Or informally....
Sum of their ages 10 years from now is 52.
So sum of their ages now is 52-20 = 32.
Subtract 6 years from David's age to make them the same age; the sum of their ages is now 32-6 = 26.
Then Delia's age is 26/2 = 13.
Add the 6 years back on to David's age to find out he is 13+6 = 19.
