For this case we must obtain 18% of 1350. For this, we make a rule of three.
1350 -----------> 100%
x -----------------> 18%
Where the variable "x" represents the amount of Theresa's tip.
[tex]x = \frac {18 * 1350} {100}\\x = 243[/tex]
Thus, Theresa's tip, based on a total sale of $ 1350, is $ 243.
Answer:
$ 243.
