Ricardo's old toaster can hold at most two slices of bread and toast them on one side at a time. He wants his bread toasted on both sides and buttered on one side.

It takes:

• 3 seconds to put each slice into the toaster and,
• 30 seconds to toast one side of 1 or 2 slices and,
• 3 seconds to reverse a slice and,
• 12 seconds to butter one side (that side must already be toasted).
• 3 seconds to remove a slice from the toaster without putting it back in reverse.

Assuming that, only one of these operations can be done at a time:

In how short a time can Ricardo toast and butter three slices?