Answer:
20.5 and 21.5
Step-by-step explanation:
It says 2 significant figures so the least it can possibly be is 0.5 less and the most it can be is 0.5 more as if it was, lets say 20.4 it would round down to 20 not 21.
For an amount of sales of $5,000, the two salary choice will be equal
Let the amount of sales be $x
The 3% she will receive will be;

We add this to the base salary and equate to the former monthy salary
We have this as;
(3m - 4n - 7) - (8m + n - 6)
3m - 8m = - 5m
-4n - n = -5n
-7 - (-6) = -7 + 6 = -1
-5m - 5n - 1 is your answer
hope this helps