Answer: a + ( 2a - 7 ) = 41
Explanation:
Let be "a" the Nicci's age and "s" the Nicci's sister.
You know that the sum of Nicci's age and her sister's age is 41. This can be represented with the following equation:
a + 8 = 41
And knowing that Nicci's sister is 7 years less than twice Nicci's age, you can write another equation to represent this:
8 = 2a - 7
Now, substitute the second equation into the first equation in order to find the equation that represents this relationship.
Then, this is:
a + ( 2a - 7 ) = 41
Hope it helps...