Baritone saxophonist, composer, and arranger; also an important collaborator on The Birth of the Cool sessions; he went on to lead his own piano-less quartet with West Coast trumpeter Chet Baker, establishing his own particular style of "cool":.

Explanation:

Gerry Mulligan was American jazz compser, clarinestist and saxophonist.

He was born in queens village  in Queens, New York and was active from 1946 till 1996 He is one of the most famous jazz baritone saxophonists. He worked with Miles Davis, Claude Thornhill and others. His piano less quartet with Chet Baker is still considered to be one of the best cool jazz group. Many of his compositions became jazz standards e.g Walking Shoes.

.

The answer is SA = (1/2)(5)(12) + (1/2)(5)(12) + (5)(2) + (12)(2) + (13)(2)