How can i use decimal models to subtract decimals

If the endpoints of the diameter of a circle are (8, 6) and (2,0), what is the standard form equation of the circle? a) (x + 5)2 + (y + 3)2 = 18 (x + 5)2 + (y + 3)2 = 3.72 (x - 5)2 + (y - 3)2 = 18 d) (x - 5)2 + (y - 3)2 = 32

You eat $0.85 for every cup of hot chocolate you sell. how many cups do you need to sell to earn $55.25

Can someone me and explain..will award brainlest!