Question 240769
There are several keys to these problems:<ul><li>The "is" translates into an equals sign.</li><li>The "of" translates into a multiplication symbol: "*".</li><li>The unknown number is "x" (or what ever variable you prefer).</li><li>Use the fraction or decimal version of a percent. For example, 15% us 15/100 (which reduces to 3/20) or 0.15.</li></li>If the unknown is the percent use x/100.</li></ul>
Let's try this on your problems:
What is 80% of 14?
This translates into:
{{{x = (80/100) * 14}}}
To find x all we have to do is simplify the right side. 80/100 reduces to 4/5:
{{{x = (4/5)*14}}}}
Multiplying 4/5 and 14 we get:
{{{x = 56/5}}}
As a mixed number this is {{{11&1/5}}}. As a decimal this is 11.2. So 80% of 14 is {{{11&1/5}}}<br>
15 is what percent of 45?
This translates into:
{{{15 = (x/100) * 45}}}
Simplifying the right side we get:
{{{15 = (9/20)x}}}
To solve for x we will multiply both sides by the reciprocal of 9/20:
{{{(20/9)(15) = (20/9)(9/20)x}}}
This simplifies to
{{{100/3 = x}}}
As a mixed number this is {{{33&1/3}}}. As a decimal this is 33.333.... (repeating 3's). So 15 is {{{33&1/3}}}% of 45.