Example

Example: Solving Veronica's Part-Time Jobs Application with a Linear Inequality in Two Variables

To find valid solutions for a financial requirement involving two distinct sources of income, an algebraic model using a linear inequality in two variables can be graphed. Consider Veronica, whose job at a day spa pays $10 an hour and whose administrative assistant job pays $17.50 an hour. She needs to earn at least $280 a week. Translate into an inequality: Let xx be the day spa hours and yy be the administrative assistant hours. The conditional model is 10x+17.50y28010x + 17.50y \geq 280. Graph the inequality: Find the boundary line by converting to slope-intercept form. Subtracting 10x10x gives 17.50y10x+28017.50y \geq -10x + 280. Dividing by 17.50 yields y1017.50x+16y \geq -\frac{10}{17.50}x + 16, which simplifies to y47x+16y \geq -\frac{4}{7}x + 16. Graph the solid boundary line corresponding to this equation and shade the solution region above the line. Any valid ordered pair within the shaded area represents a combination of hours Veronica can work at each job to earn at least $280.

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Updated 2026-06-25

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