-41 1/10 or -41.1; Since he is already 32 1/2 below the surface then if he descends another 8 3/5, that means he is going deeper. For tyou can subtract.
-32 1/2 - 8 3/5
-40 (whole number)
1/2-3/5
-5/10-6/10 (multiplied to GCF of 10)
-11/10 or -1.1 (fraction)
-41 1/10 or -41.1