In the number 35.3816, the underlined three is the other three.

100 times bigger 

Explanation:
The given number is:
35.3186

Let's take a look at the first 3 on the left (the one in bold).
We will find that this 3 is in the tens position (10)

Now, let's take a look at the other 3 (the one directly after the point).
We will find that this 3 is in the tenth position (0.1)

Now, when multiplying the digit in the tenth position by 100, this digit would be in the tens position.
This means that the difference between the two positions is 100

Based on this:
The 3 in the tens position is 100 times greater than the 3 in the tenth position.

Hope this helps :)

On monday,mrs.wise bought 3 lbs of apples at $4per lb= 4*3=$12on tuesday ,20%off and she buy 5 lbs of apples = $4-20%=3.20*5lb=$16example: other wise when she buy 5lbs on monday she have to spend 4*5=20