What property is m∠GKH+m∠GKH=180°

This is about circle theorems. someone asap : (

Which exponential function has an initial value of 2? f(x) = 2(3x) f(x) = 3(2x)

Atruck can be rented from company a $50 a day plus $0.60 per mile. company b charges $20 a day plus $0.80 per mile to rent the same truck. find the number of miles in a day at which the rental costs for company a and company b are the same