Today, while studying solid state I came across a question it says, suppose there is a cube and atoms are present on the A(corners,face centers) and B(edge centres) of the cube I just simply checked the contribution and tried to find the ratio between A and B which I got as 4:3 but I was surprised to see answer is not that. Can someone point out where I am going wrong.

Actually we not to find the contribution of A and B