For each of the following problems, set up an equation and solve.
(a) After reducing the regular selling price by one-fifth, Star Electronics sold a TV set for $192. What was the regular selling price?
(b) The weaving department of a factory occupies 400 square meters more than two times the floor space occupied by the shipping department. The total floor space occupied by both departments is 6700 square meters. Determine the floor space occupied by the weaving department.
(c) A machine requires three hours to make a unit of Product A and five hours to make a unit of Product B. The machine operated for 395 hours, producing a total of 95 units. How many units of Product B were produced?
(d) You invested a sum of money in a bank certificate yielding an annual return of one-twelfth of the sum invested. A second sum of money invested in a credit union certificate yields an annual return of one-ninth of the sum invested. The credit union investment is $500 more than two-thirds of the bank investment, and the total annual return is $1000. What is the sum of money you invested in the credit union certificate?