Estimate a 15% tip for a $60 bill​

The population of a small rural town in the year 2006 was 2,459. the population can be modeled by the function below, where f(x residents and t is the number of years elapsed since 2006. f(t) = 2,459(0.92)

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.

An engineer scale model shows a building that is 3 inches tall. if the scale is 1 inch = 600 feet, how tall is the actual building?