It is given Roberta makes 9$ an hour plus a 12.5% commission selling jewelry and she sells 380$ worth of jewelry in 8 hours.
Let the number of hours Roberta work be x hours .
Amount earned in x hours shift =9* x + 12.5% of the amount of jewelry sold.
Number of hours worked by Roberta if 9 hours and Jewelry worth 380$ is sold by her .
Substituting these values in the above equation :
Amount earned in 8 hours shift= 9 *8+12.5% 0f 380
= 72+0.125 *380 ( 12.5%=0.125)
=72+47.5
=119.5
Amount earned by Roberta in 8 hours is 119.5$
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