When incomes are directly related to prices, real income will remain relatively unchanged.

When - subordinate conjunction introducing a dependent clause

incomes - subject

are - auxiliary verb

directly - adverb modifying the verb "related"

related - main verb

to - preposition

prices - object of the preposition "to"

real income - subject complement

will remain - auxiliary verb + main verb

relatively - adverb modifying "unchanged"

unchanged - adjective complement