A production process uses a $2-$step operation. Tomorrow's work will consist of seven orders as shown below. Determine a job sequence that will minimize the total time required. What is the minimum total time?

Order Step$1$ Step$2$

A $1\mathrm{.}21\mathrm{.}4$

B $21\mathrm{.}3$

C $20\mathrm{.}8$

D $1\mathrm{.}71\mathrm{.}5$

E $1\mathrm{.}61\mathrm{.}8$

F $2\mathrm{.}21\mathrm{.}75$

G $1\mathrm{.}31\mathrm{.}4$

a$.$

$12\mathrm{.}80$

b$.$

$12\mathrm{.}55$

c$.$

$13\mathrm{.}45$

d$.$

$13\mathrm{.}15$