Ireally need so me i'm completely lost

For the following geometric sequence, find the recursive formula. {-80, 20, -5, } i need : ')

Afactory buys 10% of its components from suppliers b and the rest from supplier c. it is known that 6% of the components it buys are faulty. of the components brought from suppliers a,9% are faulty and of the components bought from suppliers b, 3% are faulty. find the percentage of components bought from supplier c that are faulty.

(30 points). the population of a city is 45,000 and decreases 2% each year. if the trend continues, what will the population be aer 15 yrs