If line ab = 3 centimeters, and line bc = 4 centimeters, which does line ac equal?

Could somebody me with this radical simplification?

Jordan got 27 out of 90 correct on his test . what fraction of the marks did her get correct

The table shows the number of students who signed up for different after school activities. activity students cooking 9 chess 4 photography 8 robotics 11 select the true statements about the information in the table.