Find the unit for me and my friend

The diameter of a circular chip is doubled to use in a new board game. the area of the new chip will be

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?