X is unknown. There’s no answer to the problem stating what X could possibly be.
5(n + 3) + 4n
5n + 15 + 4n Distributive property
5n + 4n = 9n Combine like terms
9n + 15 Final answer
Answer: 9n + 15
ANSWER
The solution is

EXPLANATION
The given equations are:

and

We multiply equation 1 by 3 to get,

We multiply equation 2 also by 2 to get,

We subtract equation 4 from equation 3 to get,

This implies that,

We put this value of y into any of the equations say equation 2

Simplify

Group like terms

Simplify,

Divide both sides by 3 to get,

Therefore the solution is

The correct answer is option D.

Scientific notation for above vLue is :