Math 6. can anyone me with this writing and solving equation as soon as possible?
a cd costs $14.95. this is $7.55 less than the cost of a dvd. write and solve a subtraction equation to find the cost of the dvd.

i know that the cd is $14.95, and that i need to subtract $7.55 from the $14.95 and my answer would be $7.40. however, i need to have a write and solve equation to answer this !

Refer to interactive solution 17.45 to review a method by which this problem can be solved. the fundamental frequencies of two air columns are the same. column a is open at both ends, while column b is open at only one end. the length of column a is 0.504 m. what is the length of column b?

Determine which expressions represent real numbers and which expressions represent complex number. asaaap! plis!

Quick! a survey of 57 customers was taken at a bookstore regarding the types of books purchased. the survey found that 33 customers purchased mysteries, 25 purchased science fiction, 18 purchased romance novels, 12 purchased mysteries and science fiction, 9 purchased mysteries and romance novels, 6 purchased science fiction and romance novels, and 2 purchased all three types of books. a) how many of the customers surveyed purchased only mysteries? b) how many purchased mysteries and science fiction, but not romance novels? c) how many purchased mysteries or science fiction? d) how many purchased mysteries or science fiction, but not romance novels? e) how many purchased exactly two types of books?