Relational Expressions and Substitution

The tie between two quantities is written as an expression with the unknown quantity set as x, and figures are then put into that expression to reach an answer, in Word Problems that come three questions to a set. Scenes such as the weight of nails or the price of a book, a line diagram joining home, a park and a school, and Calculation on the Perimeter of an Equilateral Triangle and the Perimeter of a Square stand together.

The third question runs the other way, finding x back from a value of y, yet papers line up that multiply as they did on the second. Put the x found back into the expression set up and calculate y, and whether it matches the y written in the question brings out the difference of direction.

In Expressing the Area of a Shape with a Letter the run of three questions to a set stays, while the scenes, which had included weight and distance, narrow to the areas of six figures alone. Expression shapes needing more than a multiplication turn up there too.