the number of students failed in chemistry exam is changed from 20 to 12 . what is the decrease percent?

40%

Step-by-step explanation:

percentage decrease

=

Percentage decrease

You could also first calculate the percentage change then get rid of the negative sign to find percentage decrease.

percentage change

= (new -original)/original ×100%

= (12 -20)/20 ×100%

= -40%

Thus, percentage decrease= 40%.

p=40%

Step-by-step explanation:

20-12=8

8=p/100 *20=20p/100=p/5

p=8*5=40

p=40

answer:   expression= p+p*d%

price reduction + sale price = $625

sale price: $p+$p*d%

where d% is the percentage of discount

step-by-step explanation:

original price = p

price went down by $150 price reduction $p*d%

sale price= $ 475

therefore the price before sale is: $625

and the expression that shows the price before sale is: p+p*d%