Read it again any time, including while you work through the exercises.
You know how to solve an equation. But in real life, nobody hands you a ready-made equation: they tell you a story. "Julie has three times as many marbles as Tom, together they have 48..." Turning a word problem into an equation means translating that story into the language of mathematics. It is one of the most useful powers in all of algebra.
The method fits in four steps. One: choose the unknown, the mystery quantity, and write it down clearly ("let x be Tom's number of marbles"). Two: express the other quantities of the story in terms of x (Julie has 3x). Three: find the sentence in the problem that ties everything together, and turn it into an equality (48 altogether, so x + 3x = 48). Four: solve, then check against the original story.
Choosing the unknown is strategic: almost always pick the SMALLEST quantity in the story. If Julie has three times as many marbles as Tom, let x be Tom's count: Julie simply becomes 3x. If you let x be Julie's count, Tom becomes x/3 and fractions crash the party for no reason.
The final check is your professional signature: do not just check your algebra, reread the PROBLEM with your solution. Tom has 12 marbles, Julie 36, total 48, and 36 is indeed triple 12. Everything fits? Then you have won. A result that contradicts the story (a negative age, a zero length) is an alarm bell: the equation itself needs another look.
In this lesson you will practise on mystery numbers, perimeters, sums of money and consecutive integers. Every time, the same ritual: unknown, translation, equation, check.