Good question! The correct answer is a) increases and b) increases.
While the pair of answers a) decreases and b) decreases or the pair a) stays the same and b) stays the same would be technically correct answers, this is the best way of describing the trend of the scatter plot; typically, trends are described by how the dependent or y-variable responds to the independent or x-variable increasing.
Length x width is the formula. so 18 x 18 for 7. 22 x 24 for 8. and 8 would probably be 5 x 5 to equal 20. so the length and width would be 5 and 5 because 20 is the area