4. \( 5 x+y<7 ;(2,-2) \)

Let's explore the history of inequalities! Inequalities have been used since ancient times, with mathematicians like Indian scholar Brahmagupta (c. 598–668) discussing equations and inequalities in his texts. The development of symbols for inequalities—like "<" and ">"—came later in the 16th century, making it easier for us to express relationships between numbers and variables without writing out long sentences. Now, when applying inequalities in the real world, they can help us make decisions based on budget constraints, for example. Suppose you're planning an event and need to keep costs below a certain amount. By setting up inequalities involving expenses—you can quickly visualize options and find the best way to allocate your budget without exceeding limits. It’s like being a math magician for making choices!