how come (240+3xsquare)/x -24

come become xsquare-24x+80?
I know 3 x square & 240 is divided by 3,but how do I get from -24 to -24x?

anyone can help me confirm it?is (a)
30/x + 2?
(b) I don't know how to get though

\frac{240+3x^{2}}{x}-24

Multiply by x:

240+3x^{2}-24x

Divide by 3:

x^{2}-8x+80