First write the question out in equation form.

\(\displaystyle 30\% \times a\)

Since the question states that 

\(\displaystyle a=12\)

the equation becomes,

\(\displaystyle 30\%\times 12\).

From here, convert 30% into a fraction.

\(\displaystyle 30\%\Rightarrow\frac{30}{100}=\frac{3}{10}\)

Substituting the fraction in for the percentage the equation becomes,

\(\displaystyle \frac{3}{10}\times 12\)

\(\displaystyle \frac{3\times12}{10}=\frac{36}{10}=\frac{18}{5}\)

Since a percentage is a "part of 100" to turn it into a fraction we take the original number in the percent and place it over 100:

\(\displaystyle 22\%\rightarrow \frac{22}{100}\)

From here, simplify the fraction as necessary:

\(\displaystyle \frac{22}{100}\div \frac{2}{2}=\frac{11}{50}\)

Since a percentage is a "part of 100" to turn it into a fraction we take the original number in the percent and place it over 100:

\(\displaystyle 55\%\rightarrow \frac{55}{100}\)

From here, simplify the fraction as necessary:

\(\displaystyle \frac{55}{100}\div \frac{5}{5}=\frac{11}{20}\)

Convert the improper fraction \(\displaystyle \frac{7}{5}\) to the mixed numeral \(\displaystyle 1\frac{2}{5}\) or as the decimal \(\displaystyle 1.4\).  \(\displaystyle 1.4\) as a percentage is \(\displaystyle 140\%\)

First, we will determine the total number of ballots:

\(\displaystyle 4+4+5+7+12+13=45\hspace{1 mm}ballots\)

Since there are two four year olds, and this question is asking the probability of the chosen child being four, the probability is:

\(\displaystyle \frac{4+4}{45}=\frac{8}{45}=0.1\overline{7}=17.\overline{7}\%\)

The first hen lays 8 brown eggs: 2/5 * 20 = 8

The second lays 5 brown eggs: 1/4 * 20 = 5

The third lays 6 brown eggs: 3/10 * 20 = 6

Add up the brown eggs and divide by 60, the total number of eggs:

19/60 = 0.31666667 = 31.67%, or 32%.

The percent is a number over 100.  Set up the proportion to find the unknown value.

\(\displaystyle \frac{5}{12}=\frac{x}{100}\)

\(\displaystyle 12x=500\)

\(\displaystyle x=\frac{500}{12}=41.67\%\)

The closest answer is \(\displaystyle 42\%\).

Reduce the fraction.

\(\displaystyle \frac{12}{18} = \frac{6\times 2}{6\times 3}= \frac{2}{3}\)

Set up the proportion such that some number is over 100.

\(\displaystyle \frac{2}{3}=\frac{x}{100}\)

Solve for \(\displaystyle x\), which is the percent.

\(\displaystyle 3x=200\)

\(\displaystyle x=\frac{200}{3}= 66.7\%\)

To turn this fraction into a percent, let's write it as a decimal first. 

\(\displaystyle \frac{3}{15} = 0.20\)

Now, let's set up a proportion to make this a percent.

\(\displaystyle \frac{0.2}{1} = \frac{x}{100}\)

\(\displaystyle x=20\)

Therefore, our answer is \(\displaystyle 20\%\). 

Your share = 45% of 100 pounds of bacon = .45 * 100 = 45 pounds

For mom and cousin = 30% + 25% =  55%

Percent left for you = 100% - 55% = 45%

45% of 45 pounds = .45 * 45 = 20.25 pounds