The problem is A flower shop sells bouquets in a basic arrangement and and in a deluxe arrangement. The table shows the sales of each type for d days

The Table
Basic arrangement 17$ number sold 8d-7
Deluxe Arrangement 25$
Number sold 3d+6

Write an expression that represents the difference between the number of basic arrangements and deluxe arrangements sold

The distance between the two points is calculated through the equation, 
                                 d = √((x₂ - x₁)² + (y₂ - y₁)²)
Substituting,
                                  d = √(12 - 3)² + (5 - -1)² = 10.82 
Then, we divide this value by 6 which gives us the answer of 1.8. 
    (point B)              d = √(x₃ - 3)² + (y₃ - -1)² = 9
     (point Z)             d = √(x₃ - 12)² + (y₃ - 5)² = 1.82

The values of x₃ and y₃ in the equations above are 10.5 and 4. Thus, the coordinates are (10.5, 4).