IX. \( 10 x+7=77 \)

To solve the equation \( 10x + 7 = 77 \), start by isolating the term with \( x \). Subtract 7 from both sides to get \( 10x = 70 \). Then, divide both sides by 10 to find \( x = 7 \). Voilà! You've uncovered the mystery of \( x \). In the world of algebra, understanding how to isolate variables is a key skill! Whether balancing a budget or determining the size of ingredients for a recipe, equations like this pop up all the time. So next time you find \( x \) missing from a task, just remember this simple approach!