Formatting first:
Step 1: (6.2 − 1.6) − 4.4 + 7.8
Step 2: 6.2 + (− 1.6 − 4.4) + 7.8 (commutative property)
Step 3: 6.2 − 6 + 7.8
Step 4: −14 − 6 = 8 (commutative property)
Step 5: 14 − 6 = 8
Step 2 is the associative property (a+b)+c=a+(b+c)
Step 4 is just wrong with -14 instead of 14; seems corrected in step 5.
Answer: He wrote commutative instead of associative in Step 2.