Question

Sergei says that 10% of a number will always be less than 20% of any other number.

Answer 1

That statement is only true sometimes.  If you use 500 and 10, 10% of 500 is 50, while 20% of 10 is only 2.  Clearly, 50 is larger than 2.

Answer 2

The statement is true sometimes

Explanation:

Let

x------> a number

y-----> another number

we have that

`0.10x < 0.20y` ----> inequality that represent the situation

Verify

For
`x=100, y=200`

substitute in the inequality the values of x and y

`0.10(100) < 0.20(200)`

`10 < 40` -----> is true

For
`x=600, y=100`

substitute in the inequality the values of x and y

`0.10(600) < 0.20(100)`

`60 < 20` -----> is not true

Therefore

The inequality is true sometimes