Plzz me with this one i dont know what to do on this one 5x- 3(x-2)

hep the ratio of the weight of shawn's dog to the weight of andy's dog is 5: 7 shawn's cat weight 23kg approimately how much does andy's dog weigh

I’m stuck on this equation, anyone got the answer?

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