Question 26872
This is a matter of converting English into algebra, so let's look at it word by word.

"Latoya" - let's create the variable L to stand for Latoya's age
"is" - means "="
"twice as old as" means we will be multiplying by 2.
"her cousin" - we need a new variable C to represent her cousin's age
"was three years ago" - 3 years ago means we will have to subtract 3

So our first sentence boils down to "Latoya (L) is (=) twice as old as (2 times) her cousin (C) three years ago (-3)" or:
{{{L=2C-3}}}
The second part says:
"The sum of" - means we'll be adding together
"their ages now" - L & C
"is" - still means equals
"15" - 15
This translates to:
{{{L+C=15}}}
Now you have two equations, that you can solve either through elimination, substitution, graphing, or any other way you've been taught to solve for the ages of each L & C.