The best linear model for the data would be the best line of fit for the data. We can eliminate the rightmost graphs as they have no correlation with the data.
Between the leftmost graphs, we can see that the top left graph would be choice as it encompasses most of the data/is more of the data's average than the bottom one.
So perimeter is equal to 2 lengths and 2 width so the equation would be P=2L+2W. you know width so you plug in 5 for W then solve for L and you should get L=3
