The table below gives the prices for Magic Carpet carpet cleaning
Size of house
Steam clean
Steam clean +
protective finish
One-story
$40
$65
Two-story
$60
$85
4. Huang owns 12 houses that need to have their carpets steam
cleaned with a protective finish before he can rent them out.
Huang pays a total of $840. How many two-story houses
did he clean?
A. 0
B. 2
C. 3
D. 8
E.
9

Can someone me and do the problem plz so i can understand it more better

Need on this geometry question. explain how you did it.

Suppose you are an avid reader and are looking to save money on the cost of books instead of paying about $20 for each book, you decide to look into purchasing a kindle for $120 you can purchase e-books for about $5 each 1. find the slope-intercept equation for the cost of the hard copy of books using x to represent the number of books 2. find the slope-intercept equation for the cost of the kindle with cost of e-books using x to represent the number of books