If the labor costs were $1,500,000 last year and $1,300,000 this year, what percentage decrease was achieved? ( round to the nearest percent )

The percentage decrease was 13%. If you subtract 1,300,000 from 1,500,000, you will get 200,000. You then divide 200,000 by the original number 1500,000 and you will get 0.13333333333333...
After you do that multiply that number by 100 and you will get your percentage.
(1,500,000-1,300,000=200,000)
(1,500,000/200,000=0.13333333333...)
(0.1333333333333X100=13.33333333...)
and then just round