How should compound words be typed in a business letter?

There are three types of compound nouns in English:

• closed or solid, bedroom, bathtub, doorway
• hyphenate, mother-in-law, able-bodied, start-up
• open or spaced, child care, ground water, vice president

Compound nouns should be typed as their standard use, found in a dictionary (on line or hard copy). See the link below for additional information on compound Words.