DEAR BOB: I presently own five apartment houses, all in the best areas of town. But in the last year I've found it is nearly impossible to buy apartment houses in good areas that give a decent return on investment. Do you have any suggestions as to how I can find apartment houses that make better financial sense? Kiley A., Maryland.

DEAR KILEY: Rents in most areas have not kept pace with rising expenses for operating apartment houses. The result is many apartment houses barely break even after paying expenses and mortgage payments.

However, "bread and butter" apartments usually still produce a good investment return to the owner while offering economical rents for their tenants. A "bread and butter" apartment house is one catering to working class tenants, not the upper middle class tenants you probably have in your present buildings. You'll find "bread and butter" apartments in middle class neighborhoods where the tenants expect just decent housing at modest rents.

DEAR BOB: I enjoyed your recent article about why depreciation is such a great tax benefit. Why can only a depreciable building's value be depreciated but not the value of the land? Charles C., Maryland.

DEAR CHARLES: Land values are not depreciable because, theoretically, land never wears out or becomes obsolete. Land beneath a depreciable building isn't subject to wear, tear, or obsolescence as is the building it supports. However, land used for farming gets special tax deductions for conservation expenses. If the land is subject to mineral withdrawal, then tax deductions for depletion are allowed in many situations.

Readers desiring a copy of the report "How to Maximize Your Profit When Selling Your Residence," including 1976 tax law changes, may send 10 cents in coin and a STAMPED self-addressed envelope to Robert J. Bruss, P.O. Box 6710, San Francisco, Calif. 94101.