Dave and Ellen are newly married and living in their first house. The yearly premium on their homeowner's insurance policy is $550 for the coverage they need. Their insurance company offers an annual discount of 6 percent if they install dead-bolt locks on all exterior doors. The couple can also receive an annual discount of 4 percent if they install smoke detectors on each floor. They have contacted a locksmith, who will provide and install dead-bolt locks on the two exterior doors for $78 each. At the local hardware store, smoke detectors cost $20 each, and the new house has two floors. Dave and Ellen can install the smoke detectors themselves. a. What discount will Dave and Ellen receive if they install the dead-boit locks? (Round your answer to 2 decimal places.) b. What discount will Dave and Ellen receive if they install smoke detectors