Question

A number first decreases by 60%, then again decreases by 80%. Find the percentage decrease on the whole.

Answer 1

Answer:

Let the number be 100

In first condition : Decrease = 40% of 100

= 40/100 × 100

= 40

∴  Number after this decrease = 100 – 40 = 60

In second condition :

Decrease = 60% of 40

= 60/100 × 40

= 24

∴  Number after the 2nd decrease = 40 – 24 = 16

⇒  Total decrease on the whole = 40 + 24 = 64

∴  Percentage decrease on the whole = 64/100 × 100

= 64%

Step-by-step explanation:

Hope It Helps You !!

Answer 2

Answer:

92%

Step-by-step explanation:

Let the number be x

According to question,

1st X decrease by 60%

then x becomes X× 40/100

2nd again decrease by 80%

then X becomes X× (40/100)×(20/100) = X×(8/100)= X×8%

Percentage decrease on the whole is (100-8)% = 92%