Algebra-1

Question Analysis
This question assesses the student's understanding of the substitution method by providing a system where one equation is already in the form .

Key Concept Explanation
The substitution method involves expressing one variable in terms of the other and then substituting this expression into the other equation to eliminate one of the variables.

Step-by-step Solution
1. The second equation is already in the form .
2. Substitute into the first equation: .
3. Simplify to get , so .
4. Solve for