SOLUTION: i'm confused as to how to do these problems. for example : what is 80% of 14? or 15 is what percent of 45?

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Question 240769: i'm confused as to how to do these problems. for example : what is 80% of 14? or 15 is what percent of 45?
Found 2 solutions by edjones, jsmallt9:
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
14*.8=11.2
.
Let the percent = 100x
45x=15
x=15/45=1/3
1/3 * 100=100/3 % = 33 1/3 %
.
Ed

Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
There are several keys to these problems:
  • The "is" translates into an equals sign.
  • The "of" translates into a multiplication symbol: "*".
  • The unknown number is "x" (or what ever variable you prefer).
  • Use the fraction or decimal version of a percent. For example, 15% us 15/100 (which reduces to 3/20) or 0.15.
    • If the unknown is the percent use x/100.

Let's try this on your problems:
What is 80% of 14?
This translates into:
x+=+%2880%2F100%29+%2A+14
To find x all we have to do is simplify the right side. 80/100 reduces to 4/5:
x+=+%284%2F5%29%2A14}
Multiplying 4/5 and 14 we get:
x+=+56%2F5
As a mixed number this is 11%261%2F5. As a decimal this is 11.2. So 80% of 14 is 11%261%2F5

15 is what percent of 45?
This translates into:
15+=+%28x%2F100%29+%2A+45
Simplifying the right side we get:
15+=+%289%2F20%29x
To solve for x we will multiply both sides by the reciprocal of 9/20:
%2820%2F9%29%2815%29+=+%2820%2F9%29%289%2F20%29x
This simplifies to
100%2F3+=+x
As a mixed number this is 33%261%2F3. As a decimal this is 33.333.... (repeating 3's). So 15 is 33%261%2F3% of 45.