130.40 - 129.60 equals

Answer 1

0.8000000000000114

Answer 2

To add/subtract numbers with a decimal, line them up with the decimals in a column:

130.40

-129.60

---------

The letters and numbers don't line up well on the screen, so you have to line them up on paper properly!

Then, just fill in extra zeroes so you always have two numbers to add/subtract, and do it normally.

Finally, fit in the decimal place in the same column in your answer.