Explain how to get the variable alone in each question k-13=29

Mindy bought 5/8 pound of almonds and a 3/4 pound of walnuts. which pair of fraction cannot be used to find how many pounds of nuts she bought in all.

Sara needs to take a taxi to get to the movies the taxi charges $4.00 for the first mile and then $2.75 for each mile after that if the total charge is $20.50 then how far was sara’s taxi ride to the movie

If 25% of y is 30, what is 60% of y?