Addition : Addition is the mathematical operation that describes increasing a number by an amount equal to a second number. The mathematical symbol for addition is the plus sign $+.$ The term addition is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.

Count : To count means to find out the number of objects by adding one for every object.

See how often you have to add 1 to reach 5 starting at 3.

The correct answer is 2. Counting 3, 4, 5 reaches 5 after 2 steps.

Area : The amount of unit squares that is needed to cover a 2-dimensional shape.

Centimeter : A centimeter ($cm$) is $\frac{1}{100}$ of a meter.

Length : Length is the attribute of a one-dimensional shape that can be measured with a measuring tape.

Square : A square is a quadrilateral with four right angles and four equal length sides. A square is a special case of a rectangle and a special case of a rhombus.

Square centimeter : Square centimeter or $cm^2$ is a unit of measurement for measuring area. 1 square centimeter is the area of a square with side length 1 $cm,$ so 10,000 $cm^2$ are one $m^2.$

The area of a square is the square of its side length.

The correct answer is 1. The width and the length of the square are both 1 cm, so the area in square cm equals $1\cdot 1=1^2=1.$

Area : The amount of unit squares that is needed to cover a 2-dimensional shape.

Division : Division is the mathematical operation that divides objects equally into groups. More generally $x\div y$ is defined as the number that if multiplied by $y$ equals $x.$

Inch : An inch or $in$ is a unit of measurement for length. 12 inches are one foot and 1 inch is about 2.54 $cm.$

Length : Length is the attribute of a one-dimensional shape that can be measured with a measuring tape.

Multiplication : Multiplication is the mathematical operation that is a shorthand for adding the same amount several times. For example $3\cdot 4=4+4+4=12.$

Rectangle : A rectangle is a quadrilateral with 4 right angles. Two opposing sides in a rectangle have the same length. They are sometimes referred to as the width and the length of the rectangle. To calculate the area of an rectangle one can multiply the width of the rectangle by the length of the rectangle. A square is the special case of a rectangle in which all side lengths are the same. Every rectangle is a parallelogram.

Reduced fraction : A reduced fraction (or simplified fraction or fraction in simplified form or fraction in simplest form) is a fraction $\frac{a}{b}$ such that $a$ and $b$ do not have any common factors bigger than 1. For example the reduced fraction of the fraction $\frac{4}{6}$ is $\frac{2}{3}.$

Square inch : Square inch is a unit of measurement for measuring area. 1 square inch is the area of a square with side length 1 inch. 144 square inches are 1 square foot.

To get the width you have to divide the area of the rectangle by its length.

The correct answer is 3/5. The area of a rectangle is calculated by multiplying the width of the rectangle with the length of the rectangle. This means that you can calculate the width of a rectangle by dividing the are by its length: $\frac{9}{15}\div \frac{3}{3}=\frac{9}{15}\cdot \frac{3}{3}=\frac{3}{5}.$