Answer:
Total earnings of Ruby for the month is $4020 .
Option (d) is correct .
Explanation:
As given
Ruby has a monthly salary of $1,800 and also earns 6% commission on her sales.
If Ruby had $37,000 in sales last month .
6% is written in the decimal form

= 0.06
Equation becomes
Total earnings for the month = Monthly salary + 0.06 × Sales last month
Put all the values in the above
= 1800 + 0.06 × 37000
= 1800 + 2220
= $ 4020
Therefore the total earnings of Ruby for the month is $4020 .
Option (d) is correct .