Answer:
The first option [tex]\frac{17}{21}[/tex]
Step-by-step explanation:
In order to solve this question we have to add the three fractions. In order to add the fraction we need them to have the least common dinoinator. For 3, 7, and 21 it is 21. So...
[tex]\frac{2}{3} - \frac{4}{7} + \frac{15}{21} = \frac{14}{21} - \frac{12}{21} + \frac{15}{21} = \frac{17}{21}[/tex]
