You would use a ruler to measure a shoe because a candle is most likely smaller than 12 inches, which is the size of a ruler. All of the other tools will be much larger. 

You would use a ruler to measure a taco because a taco is most likely smaller than 12 inches, which is the size of a ruler. All of the other tools will be much larger. 

$\displaystyle -50< -3< 0< \frac{1}{2}$

$\displaystyle Negative\;numbers\;are\;smaller\;than\;0.$

$\displaystyle Positive\;number\;are\;greater\;than\;0.$

isosceles: triangle with two equal sides and two equal angles

scalene: triangle with no equal sides and no equal angles

equilateral: triangle with three equal sides and three equal angles

A subset of a set $\displaystyle C$, by definition, is any set that contains no elements not in $\displaystyle C$.  Each of the following subsets can be seen to have at least one such element, which is underlined here:

$\displaystyle \left \{ \underline{1}, 4, 8, 12, 20\right \}$

$\displaystyle \left \{ 8, \underline{9}, 10, 12, 16, 18\right \}$

$\displaystyle \left \{ 4, 6, 8, 10,\underline{ 11}, 14\right \}$

$\displaystyle \left \{ 2, 4, 6, \underline{9}, 12, 14\right \}$

The remaining set can be seen to have only elements from $\displaystyle C$:

$\displaystyle \left \{ 4, 8, 12, 16, 20\right \}\subseteq \left \{ 2, \underline{4}, 6, \underline{8}, 10, \underline{12}, 14, \underline{16}, 18, \underline{20}\right \}$

This is the correct choice.

$\displaystyle A \cup B$ is the union of sets $\displaystyle A$ and $\displaystyle B$ - the set of all elements that appear in either $\displaystyle A$ or $\displaystyle B$. These elements are:

$\displaystyle \left \{ a, b,c, d,e, f, h, i, j,k,m,p \right \}$

which is a set with twelve elements.

$\displaystyle When\: multiplying \: numbers \: by \: 11, \: the \: sum \: goes \: in\: between \: the \: two \: digits.$

$\displaystyle 43\times11=4\underline{7}3\Rightarrow 4\;\underline{4+3} \;3$

$\displaystyle 15\times11=1\underline{6}5\Rightarrow 1\;\underline{1+5} \;5$

For negative numbers, the bigger the value next to the negative sign, the smaller the number. For example, $\displaystyle -100$ is smaller than $\displaystyle -1$. 

Use the tenths digit (the one to the right of the decimal point) to order the numbers:

The negative numbers with a $\displaystyle 7$ in the tenths place are smaller than the numbers with a $\displaystyle 6$ in the tenths place.

Then, use the hundredths place to order the numbers:

$\displaystyle -0.69$ is smaller than $\displaystyle -0.66$ since $\displaystyle 9$ is larger than $\displaystyle 6$. 

$\displaystyle -0.71$ is smaller than $\displaystyle -0.70$ since $\displaystyle 1$ is larger than $\displaystyle 0$. 

A prime number has exactly two factors: 1 and itself. 85 is immediately disqualified: any number that ends in 5 has 5 as a factor.

First, use the tenths digit (the one to the right of the decimal point) to order the numbers.

The numbers with a 6 in the tenths place are smaller than the numbers with a 7 in the tenths place.

Then, use the hundredths place to order the numbers.

0.66 is smaller than 0.69 since 6 is smaller than 9.

0.70 is smaller than 0.71 since 0 is smaller than 1.