Question

2) A salesperson earns commission on the sales that she makes each month.

Answer 1

Part A
Commission total = Commission 1+ Commission 2
Where
Commision 1 = 5% of first 45000
Commission 2 = 7.5% of the amount left after $5000 is subtracted
thus 
Commision 1 = $5000x.05
                      = $250

Commission 2= $3000 x.075
                        = $225
Commission total = $250+$225
                              = $475
The total commission she earned is $475ion

Part B.
Total sales = Sales with 5% commission+Sales with 7.5% commission
Sales with 5%commission= $5000
Commision At 7.5% = Total commision -Commission with 5%
                           =    $1375-$250
              Sales x.075=  $1125
              Sales with 7.5% commision = $15000
Total sales = $5000+$15000
Total sales = $20000
Total sales for commission of $1375 is $20000