$\displaystyle 17 \frac{1}{2} \%$ of $\displaystyle 17 \frac{1}{2}$  can be rewritten as 

$\displaystyle \frac{17 \frac{1}{2} }{100} \times 17 \frac{1}{2}$

$\displaystyle = \frac{35}{2} \times \frac{1}{100} \times \frac{35}{2}$

$\displaystyle = \frac{35 \times 1 \times 35}{2 \times 100 \times 2}$

$\displaystyle = \frac{1,225}{400} = \frac{1,225 \div 25}{400\div 25} = \frac{49}{16} = 3 \frac{1}{16}$

1,800% of 0.00018 is equal to

$\displaystyle \frac{1,800}{100} \times 0.00018 = 18 \times 0.00018 = 0.00324$.

Taking 1.11% percent of a number is the same as multiplying it by 0.0111, so

1.11% percent of 1.11 is equal to

$\displaystyle 0.0111 \times 1.11 = 0.012321$.

If $\displaystyle 0.2$ is $\displaystyle 20\%$ of $\displaystyle x$, that means that $\displaystyle x=1$. When we plug 1 into $\displaystyle 5x+1$, the result is $\displaystyle 6$.

When given the quantity of the whole, you can determine a part using a percentage by converting the percentage to a decimal and multiplying the whole by that decimal.  

$\displaystyle 320\times0.60=192$

Substitute in the proportion:

$\displaystyle \frac{part}{whole} = \frac{x}{300}$

$\displaystyle \frac{percent}{100} = \frac{60}{100}$

$\displaystyle \frac{x}{300} = \frac{60}{100}$

Cross multiply:

$\displaystyle 18,000 = 100x$

$\displaystyle x = 180$

To determine the number that is 85% of 560, convert the percentage to a decimal:

$\displaystyle 85\%=\frac{85}{100}=0.85$

Then multiply:

$\displaystyle 560 \times 0.85 = 476$

The correct answer is $\displaystyle 476$

To find a percentage of a whole, we will first write the percentage as a fraction.  We know that all percentages can be written as a number over 100.  So,

$\displaystyle 30\% = \frac{30}{100}$

Now, we will multiply the fraction by the whole number.  We get

$\displaystyle \frac{30}{100} \cdot 150$

Now, we can simplify/multiply.  

We write 150 as a fraction over 1.

$\displaystyle \frac{30}{100} \cdot \frac{150}{1}$

We can cancel out the zero in 150 and the zero in 100.  

$\displaystyle \frac{30}{10} \cdot \frac{15}{1}$

We can cancel out the zero in 30 and the zero in 10.

$\displaystyle \frac{3}{1} \cdot \frac{15}{1}$

Now, we can multiply.  

$\displaystyle \frac{3 \cdot 15}{1 \cdot 1}$

$\displaystyle \frac{45}{1}$

$\displaystyle 45$

Therefore, $\displaystyle 30\%$ of $\displaystyle 150$ is $\displaystyle 45$.

First, find $\displaystyle 40\%$ of $\displaystyle \$500$:

$\displaystyle 0.4\cdot \$500=\$200$

Then, subtract this value from the whole:

$\displaystyle \$500-\$200=\$300$

To find a percentage of a whole, we will multiply the percentage by the whole number.  So,

$\displaystyle 30\%$ of $\displaystyle 270$

can be written as

$\displaystyle 30\% \cdot 270$

We know that a percentage can be written as a fraction over 100.  So, 

$\displaystyle \frac{30}{100} \cdot 270$

Now, we can solve.  

$\displaystyle \frac{30}{100} \cdot \frac{270}{1}$

We can cancel out the zero in 30 and the zero in 100.

$\displaystyle \frac{3}{10} \cdot \frac{270}{1}$

We can cancel out the zero in 10 and the zero in 270.

$\displaystyle \frac{3}{1} \cdot \frac{27}{1}$

Now, we multiply.

$\displaystyle \frac{3 \cdot 27}{1 \cdot 1}$

$\displaystyle \frac{81}{1}$

$\displaystyle 81$

Therefore, $\displaystyle 30\%$ of $\displaystyle 270$ is $\displaystyle 81$.