Answer:
$1.47/ $9.80 = 0.15
15% rate
$12.60 * 15% = $1.89
Explanation:
If her lunch cost $9.80 and she left a $1.47 tip, if we do $1.47/ $9.80 = 0.15. So 15% is our percent of tip.
(That is the cost of the first day and the tip of the second day divided.) If we want to find out how much her next tip should be, we have to multiply the percent of tip (15%) with the next days cost ($12.60.) So, $12.60 * 15%= $1.89