PERCENTAGE BASE & RATE

MATH
YOUTUBE VIDEO

NOTE: you can say 'part' instead of 'percent'

PERCENTAGE RATE & BASE

P = R * B
R = P : B
B = P : R

20 is 50% of what number?

P*  
[is]

R:
[%]

B:
[of]

PERCENTAGE RATE & BASE works the same as DISTANCE SPEED & TIME

20 is 50% of what number?

B = P : R
B = 20 : .5 
B = 40

A train traveled 300 kilometers at 120 kph. How long did it travel?

T = D : S
T = 300 : 120
T = 2.5

20 is 50% of what number?
20:B = 50:100
20*100 = B*50
2000 = B*50
2000:50 = [40]

PERCENT OF INCREASE

Part = amount of increase
Base= original amount

The number of students learning Torah increased from 250 to 300 students. What is the percent of increase?

a:b = c:d is ad = bc

R = P : B

50:250 = c:100 
is 
50*100 = 250*c
5000:250 = c

C = 20%

PERCENT OF DECREASE
aka PERCENT OF DISCOUNT
-follows the same exact formula as PERCENT OF INCREASE

A dozen roses sale for $24. What is the price per unit?
R = P : B
R = $24 : 12

Unit price is $2