Final answer:
The question contains a typo but aims to solve a system of equations using the addition method. The steps include equalizing coefficients, eliminating a variable, and solving for both variables sequentially.
Step-by-step explanation:
The goal is to solve the system of equations by the addition method. However, there appears to be a typo in the question as it is given:
2x - 7y = ?
7x - 5y = 4
Assuming the question is asking to solve the system:
2x - 7y = a (where 'a' is an unknown to be determined)
7x - 5y = 4
Here is a general approach to solving the system using the addition method:
- First, make the coefficients of one of the variables the same in both equations by finding a common multiple.
- Next, add or subtract the equations to eliminate that variable, creating an equation with one variable.
- Solve for the remaining variable.
- Substitute the found value back into one of the original equations to solve for the other variable.
Without the correct coefficients, we cannot solve this system precisely, but the steps above illustrate the addition method typically used.