Subtract Decimals: Find 39.2 - 13.421 with Proper Alignment

To avoid confusion in solving the exercise, we'll first add two zeros to the number 39.2 as follows:

$39.200\\-13.421\\$

Now let's solve the exercise in order:

Let's subtract the thousands after the decimal point:

$0-1=$

Since we cannot subtract, we'll borrow ten from the tenths digit after the decimal point (note that the hundreds digit is 0 and we cannot borrow from there)

After borrowing ten from the tenths digit, the hundreds digit will become 10 and from it we'll borrow ten to solve our exercise.

The hundreds digit will become 9 and we'll get the exercise:

$10-1=9$

Let's subtract the hundreds after the decimal point:

$9-2=7$

Let's subtract the tenths after the decimal point, remembering that we borrowed ten from it, therefore:

$2-1-4=1-4$

Since we cannot subtract, we'll borrow ten from the tens digit of the whole number and get:

$11-4=7$

Finally, let's subtract the whole numbers before the decimal point accordingly:

Remember that we borrowed ten from the tens digit, therefore:

$9-1-3=5$

$3-1=2$

And we'll get:

$39.200\\-13.421\\25.779$