What is the explicit formula 0.5,-0.1,0.02,-0.004,0.0008

Eileen purchased 3.4 pounds of apples at the total cost of $19.72. if she purchases 6.2 pounds of apples at this store, how much would it cost?

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?

How do you write 600 as a product of its prime factors (index! )