Since you're trying to get v by itself, you have to do the opposite of adding to get 7.3 on the other side. Subtracting with negative decimals can seem a little tricky, but remember to line up the decimal point. When a negative number is being subtracted, it is basically being added, but make sure to keep the negative sign on afterwards if that makes sense.
-8.9 = v + 7.3
-7.3 - 7.3
-16.2 = v
To check it, just plug in -16.2 in v and see if you get -8.9 for your answer when you add 7.3 to it! (Don't worry it should be right).
