Question

a number decreased by 7%

Answer 1

X-7/100
OR
X-0.07
Since we don't know the number we need a variable which can be any alphabet so I chose "X".
For example if it were 7 decreased by 7 percent, it would be equal to:
7 - 7/100=6.93

Answer 2

93 x
--- = ------

100 Full Number

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93(full number) = 100x
Then divide by 100

*****************

Here is an Example:

93(10) = 100x
930 = 100x
Divide each side by 100

9.3


P.S
The reason the answer isn't 7 is because it's not 70%