my math

first step the question is 18.29 -15.5

 second step change it to a plus 15.5 + __ = 18.29
third step I did a number line
step 4 I add .5 to make it 16 then I add 2.0 next I added .29 it went up to 18.29
step 5 I add it all together .5 + 2.0 + .29 = 2.79

18.29-15.5=

15.5+_=18.29

15.5         16         18.0     18.29

 +-----------I----------I-------+

       .5               2.0     .29         .5 + 2.0 + .29 = 2.79m