c) \( 4(3 x+15)=84 \)

To solve the equation \( 4(3x + 15) = 84 \), let's first simplify it by distributing the 4: \( 12x + 60 = 84 \). Next, subtract 60 from both sides to isolate the term with \( x \): \( 12x = 24 \). Finally, divide both sides by 12 to find \( x \): \( x = 2 \). Now, voilà! You’ve got the solution: \( x = 2 \). Easy peasy, right? Speaking of equations, did you know that algebra has been around for thousands of years? Ancient civilizations like the Babylonians were solving equations over 4,000 years ago! They had their own methods, which were pretty sophisticated for their time, laying the groundwork for the algebra we use today. In real-world applications, equations are everywhere! Engineers use them to design buildings and bridges, while scientists rely on them for experiments and data analysis. Even in finances, equations help manage budgets and investments. Understanding how to solve them opens up a world of possibilities in various careers!