6.
the value of a textbook is $69 and decreases at
a rate of 15% per year for 11 years. how do you write it in an exponential function?

δabc ≅ δdcb by sas because

db ≅ ac . . given (side)

bc ≅ bc . . reflexive property (side)

∠dbc ≅ ∠ acb . . alternate interior angles where transversal bc crosses parallel lines bd and ac (included angle)