The function p(x)=8x-10 shows the profit, in dollars, for selling x books.

p(10) is the profit, in dollars, from selling 10 books. Replace every copy of x with 10 and simplify

p(x) = 8x-10

p(10) = 8*10-10 every x is replaced with 10

p(10) = 80-10

p(10) = 70

So the profit is $70

Step-by-stSo it took him 4/5 of an  hour to paint 1/3  

that means there is still 2/3 to go  

so that means that he will have two times that time to paint the rest of the room

4/5    =  ?  

1/3       2/3  

using cross multiplication

(4/5)(2/3) = (1/3) (?)

8/15 = 1/3 ?

divide both sides by 1/3

so that will be 8/5

that means it will take 8/5 of an hour to complete the rest  

or 12/5 total to do entire room

Hope this helps ;)ep explanation: