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

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

All the numbers are five apart.

The correct answer is 71. Counting up by 5 from 66, we get 66, 67, 68, 69, 70, 71.

Denominator : The denominator of a fraction $\frac{a}{b}$ is the number $b$ below the fraction bar.

Equivalent fraction : Equivalent fractions are fractions that represent the same number. For example the fractions $\frac{1}{2}$ and $\frac{2}{4}$ are equivalent. One can create equivalent fractions of a fraction by multiplying or dividing both the numerator and the denominator of the fraction by the same non-zero number.

Fraction : A fraction is a number that can be written as $\frac{a}{b}$ with an integer $a$ and a natural numbers $b.$ A fraction $\frac{a}{b}$ is the result of the division $a\div b.$ Examples of fractions are $\frac{1}{2}, -\frac{2}{3}$ and $\frac{3}{2}.$

Write both fractions as equivalent fractions with denominator 70.

The correct answer is 49. $\frac{7}{7}-\frac{3}{10}=\frac{70}{70}-\frac{21}{70}=\frac{49}{70}.$

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.

Hypotenuse : The hypotenuse in a right triangle is the side of the right triangle that does not have any endpoints at the corner with the right angle. The hypotenuse is the longest side in a right triangle and its length can be calculated from the other two side lengths using the Pythagorean theorem.

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

Pythagorean theorem : The Pythagorean theorem states that in a right triangle the square of the hypotenuse $c^2$ equals the sum of the squares of the legs $a^2+b^2$. It can be used to calculate the length of a third side of a right triangle given the other two. It also can be used to calculate the lengths of diagonals in rectangles or cubes.

Right triangle : A right triangle is a triangle that has a right angle. The sides that form the right angle are called legs, the third side is called hypotenuse. The area of a right triangle is half the product of the lengths of the two legs. The Pythagorean theorem is an important theorem for right triangles that allows to calculate the third side of a right triangle given the other two.

Square root : The square root of $x$ denoted by $\sqrt{x}$ is the positive number such that $(\sqrt{x})^2=\sqrt{x}\cdot \sqrt{x}=x.$ For example $\sqrt{9}=3.$

Yard : A unit for measuring length equal to 3 feet. A yard is about $0.91$ meters.

Apply the Pythagorean theorem to the right triangle formed by two sides of the soccer pitch and the diagonal of the soccer pitch.

The correct answer is 13. Applying the Pythagorean theorem to the right triangle formed by two sides of the soccer pitch and the diagonal of the soccer pitch as hypotenuse we calculate the length of the diagonal as $\sqrt{5^2+12^2}=\sqrt{25+144}=\sqrt{169}=13.$