How do uou express a single discount rate

In order to find the percent of a number we have to multiply that number by the decimal form of the percent.

For example if we were looking for 30% of 100 we would convert our percent into a decimal form by moving the decimal point 2 spaces forward.

30.00%=0.30

Then all we simply do is multiply this decimal number times the other number.

But for this case we are finding other percentages so let's get straight to the point here.

$1,500*0.40=600

$1,500*0.25=375

$1,500*0.10=150

For the other question we repeat the same process.

$640*0.10=64

I going to stop here for a moment since we have a special case 5% To find the decimal form we have to do the same thing for all the other which is move the point 2 spaces forward. However we are going to add a 0 after we move the decimal point. (this applies for all one digit percents)

5%=0.05

$640*0.05=32

$640*0.25=160

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x = 3 ± √(5+y)