How do I proceed to solve this question?

I Do understand the question now.

Had been going about it the wrong way

Solution:

total number of blocks: (r+1) *(r)

4th row=(r)

7th column = (r+1)

answer= total - 4th row - 7th column +1

adding 1 because of the intersecting element

Answer is A

So , basically we need to remove 1 row and 1 column from the gameboard .

Initially, No. of rows = r & No. of columns = r+1, Now, removing 1 row and 1 column will make the No. of rows = r-1 and No. of columns = r. Finally, its asking us to find total No. of squares which is Rows x Columns , which equals to (r-1) x (r) = r^2-r

method 2: Choosing numbers ,

Let rows = 11(r) and columns = 12(r+1), Now, removing 1 row and 1 column thus, rows = 10 and columns = 11. Squares on board= Rows x Columns = 110. Now, pulling the value of our r= 11 in the answer choices and seeing which one will results us in 110.’