hello
to solve this problem, let's try to write out an equation to represent their age.
let Nicci's age be represented by a
2a - 7 = x.....equation 1
x = Nicci's sister's age
the sum of Nicci's age and her sister = 41
x + a = 41.....equation 2
now let's substitute x into equation 2

from the equation above, the answer is the second option.