You found $5, so it's positive. You don't put anything in the negative, because you aren't losing anything.
Answer:
The answer is 18.
Step-by-step explanation:
$8250 - $3120 = $5130
$5130/75 = $68.40
Each band member must raise $68.40
Three tenths is the same as 3/10
the sum of -2 and -28 is -30
3/10 of -30 is the same as the products of the two
3 x -30 / 10 = -90/10 = -9
Your answer is
3(-2 + -28)/10 = -9