Advanced Algebra: Example 3

Backsolving is not an option for this question since the answer choices give us the sum of x and y. We would need the individual value of just one variable, x or y, in order to use this strategy.

Nor will Picking Numbers work here. Many different numbers could be placed into the two-variable, two-equation system in the question stem for evaluation.

Only algebra remains, although the approach is not as simple as solving for a single variable. Let's try it out.