Question 1144239
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Something like this, if you want/need to use formal algebra....<br>
L = Delia now
L+6 = David now<br>
L+10 + Delia 10 years from now
L+16 = David 10 years from now<br>
(L+10)+(L+16) = 52<br>
Solve using basic algebra.<br>
Or informally....<br>
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.