Assuming you have everything imported that is needed to use Bootstrap, create a responsive structure using the grid system as described below.

Template should span the entire width of the screen.

There should be three columns. The left and right column should each take up $25\%$ the width of the screen when the viewport is anything larger than small. The middle column should take up the remaining $50\%$ of the screen.

Inside the middle column there should be two more columns, the left column taking up $75\%$ of the width of it's parent and the right column taking up the remaining $25\%$ when the viewport is anything larger than small.

All columns should stack vertically and respond when the viewport is small.