Jane altered by using 3/4 of the amount of butter called for the recipe. jane used 6 tablespoons of butter how many cups of butter did the recipe call for?

Jane has only used 3/4 of the required amount.
the amount she used is 6 tablespoons.
This means that 6 tablespoons is equivalent to 3/4
                                               
4/4 is 1 whole                                                                     
3/4 --> 6                                                                            
1/4 --->6/3                                                                       
4/4 --> 6/3 x 4 = 8 tablespoons                                                                     
we are told that 16 tablespoons is 1 cup                             
then 1 tablespoon is - 1/16 cups                               
therefore 8 tablespoons - 1/16 x 8 = 1/2 cup
                   
answer is C. 1/2 cup

It would take her 20 minutes.