Help it is a 10 point quiz

For f(x)=2x+3 and g(x)=x^2- 8 find (f+g) (x)

Valentina is subtracting from . she finds the lcd to be 15y2. what is valentina's next step?

Last month, a 770 g box of cereal was sold at a grocery store for $3.10. however, this month, the cereal manufacturer launched the same cereal in a 640 g box, which is being sold at $2.50. what is the percent change in the unit price?