Pls help and no links :-)

5,600 x 10^3 = a) 560 b) 5,000,600 c) 5,600,000 d) 56,000

Aplane flies around trip to philadelphia it flies to philadelphia at 220 miles per hour and back home with a tailwind at 280 miles per hour if the total trip takes 6.5 hours how many miles does the plane fly round trip

Two numbers have a sum of -19. one number is x. what expression represents the other number?