Angle : If two line segments (or rays) both start at a common point the opening between the two line segments is called an angle. The common point is called vertex of the angle. The size of an angle is measured in degrees.

Convex : A shape is called convex if the line segment between any two points of the shape lies within the shape. A function is called convex if for all $x,y$ and $0\leq \alpha \leq 1$ you have $f(\alpha x+(1-\alpha)y)\geq \alpha f(x) +(1-\alpha) f(y).$

Degree : For angles one degree is defined as the angle represented by a $\frac{1}{360}$ of the angle represented by a full circle. For measuring temperatures one can use either degrees Celsius or degrees Fahrenheit. In a polynomial the degree describes the highest exponent of $x$ that has a non-zero coefficient. For example the degree of $1+x+x^2$ is 2.

Diagonal : A diagonal in a quadrilateral is the line segment between a corner and its opposing corner. A diagonal in a cube (or rectangular prism) is the line segment between two corners that are not part of a same face.

Quadrilateral : A quadrilateral or quadrangle is a polygon with four corners. Rectangles, trapezoids, kites, rhombuses, squares and parallelograms are all specific kinds of quadrilaterals. The sum of the interior angles in a quadrilateral is always $360^{\circ}.$

Sum : A sum is the result of an addition.

Triangle : A triangle is a polygon with three corners and three sides. You can calculate the area of a triangle by multiplying half the length of the base by the height on that base. The sum of the interior angles in a triangle is always $180^{\circ}.$

Draw a diagonal to split the quadrilateral into two triangles.

The correct answer is 360. If you draw a diagonal, the quadrilateral is split into two triangles with the sum of the angles of the quadrilateral being equal to the sum of the angles of the two triangles. As the sum of angles in any triangle is 180 degrees, the sum of angles in any quadrilateral is 360 degrees.

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 $x.$

Quotient : A quotient is the result of a division.

Calculate the quotient of the division as 720:80=72:8

The correct answer is 9. 720:80=72:8=9.

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

Number : A number $x$ is a mathematical symbol representing a quantity.

You need to multiply the number of screws needed per toy with the number of toys to be built.

The correct answer is 80. If the factory needs 8 screws to build one toy it will need $8\cdot 10=80$ for 10 toys.