Which expression is correct? Mary owes her mom $4.50" data-lrn-mathjax-postprocessed="tru e" style="display: inline; font-style: normal; font-weight: 400; line-height: normal; font-size: 16.8px; text-indent: 0px; text-align: left; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; color: rgb(51, 51, 51); font-family: LearnosityMath, "Helvetica Neue", Helvetica, Arial, sans-serif; background-color: rgb(255, 255, 255); position: relative;">$4.50.  She borrows $2.17" data-lrn-mathjax-postprocessed="tru e" style="display: inline; font-style: normal; font-weight: 400; line-height: normal; font-size: 16.8px; text-indent: 0px; text-align: left; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; color: rgb(51, 51, 51); font-family: LearnosityMath, "Helvetica Neue", Helvetica, Arial, sans-serif; background-color: rgb(255, 255, 255); position: relative;">$2.17 more from her mom.  Which expression shows how to determine the amount, in dollars, Mary owes her mom?