Using the Slope Equation
Pick two points on the line and determine their coordinates.
Determine the difference in y-coordinates of these two points (rise).
Determine the difference in x-coordinates for these two points (run).
Divide the difference in y-coordinates by the difference in x-coordinates (rise/run or slope).
-1 - (-7) = 6
5 - (-1) = 6
11 - 5 = 6
The common difference is 6.
If you add 6 to a term, you get the next term.

This is the answers from MathPapa
40 ÷ 2.40= 16.66
the teacher can buy 16 cookies
The area of the sidewalk is 72 square units. Solution: First, multiply 10 by 12 which equals 120. Then, subtract 6x8=48. So, therefore, 120-48= 72