First rewrite the mixed number as an improper fraction:
-1 1/14 = -15/14
Now you have :
-3/7 / -15/14
When dividing by a fraction, flip the second fraction over and change divide to multiply:
-3/7 x -14/15
Now multiply top by top and bottom by bottom:
(-3 x -14) / ( 7 x 15) = 42/105
Simplify by diving each number by 21 to get the final answer :
2/5