Explanation:

 let her monthly salary be ?S.
Money spent by her = 65% of ?S 
                      = ? (S×65/100) = ?13S/20
       Money saved = ?(S-13S/20) = ?7S/20
     Therefore, 7S/20 = 2940
             S = (2940×20/7) = 8400
Therefore, Kavita's monthly salary
                                                    = 8400.