Find the slope (6,-6) and (8,8)

To prove that def ~ gfh by the sss similarity theorem using the information provided in the diagram, it would be enough additional information to know that

The price of a dozen eggs was $1.63. suppose the price increases m dollars per dozen and then the price decreases $0.12 per dozen. which expression represents the current price of eggs after the two price changes?

How do i i solve this equation? -18 = x/3 + 3