To solve proportions, follow these simple steps:
1. Cross Multiply:
Multiply the denominator of the second
fraction by the numerator of the first.
Multiply the denominator of the first fraction by the numerator of the second.
2 = x
8 = 3x
2. Divide BOTH sides by the COEFFICIENT of the VARIABLE
(The variable is the unknown amount, usually
represented by a letter or other symbol. The coefficient
is the number that the variable is multiplied
by. In this case, the variable is x
and its coefficient is 3)
8 = 3x
2.666... = x
A percent is a ratio of a number to 100 [Per = For Each....Cent = 100]
Therefore another way to think about a percent, say 30%, is 30/100.
P% = P /100
You can also write a percent as a decimal.
Remember that when you divide a decimal by 100,
the decimal point moves two places to the left.
So, for example:
45% = 45/100 = 0.45
ranging from tax and commission to percent change, discount, interest, and more.
In general, all of these problems follow a basic format:
P = Percent
N = Number
R = Result
of = multiply
Percent of a Number gives a Result
P x N
Which is equivalent to:
P = R
The important thing to remember is that your percent is always of a
(Hence Percent of a number)
this base, when you are given a choice is always the ORIGINAL amount.
Example: What is 15% of 40?
What is your percent? 15
What is your base? 40
What is your result? unknown at this point...use R
Go to your equation:
P x N
= R Substitute
all values that you know at this point.
15 x 40
Solve (any way you wish...use as a fractions, reduce, then use as fractions,
or use decimals)
Any way you do this, you should get R = 6.
15% of 40 is 6.