Greetings,
I have the solution all ready for you and will include a few lines below.
save %sp, -96, %sp
mov 17, %a_r ! initialize a
mov -3, %b_r ! initialize b
mov 3, %c_r ! initialize c
add %l0, %l1, %o0 !(a+b) into %o0
call .mul
I am looking forward to working with you!