One way to find the original ratio in terms of percetange, we can multiply a factor so that the denominator reach 100. So, let's multiply this fraction by 20, each part of it
This means that the original percentage is .
Now, we have to chose the grid that has 40 squares painted. None of the grids given in the image represents 40%.
You just need to count, the grid that has 40 squares painted, that's your answer.
The middle between two numbers is the average of those numbers. So we add those two numbers together and divide by two. And the answer is (1 + 6) / 2 = 3.5