AMC 10 2017a Problem 3

Tamara has three rows of two $6$-feet by $2$-feet flower beds in her garden. The beds are separated and also surrounded by $1$-foot-wide walkways, as shown on the diagram. What is the total area of the walkways, in square feet?

$\textbf{(A)}\ 72 \textbf{(B)}\ 78 \textbf{(C)}\ 90 \textbf{(D)}\ 120 \textbf{(E)}\ 150$