All you have to do is rotate the current dots, and bam.
8.5 is the same as 8.50, right? So just take the digit in the hundredth place of both decimals and subtract. You'd be doing 0-4 so you can go ahead and borrow a number to make 10-4, which equals 6. So without subtracting 8.5 and 4.64, you can determine that 6 will be in the hundredth place. Hope this helps!
Answer:
A number is added to fifteen
A variable increased by fifteen