42y⋅4−5⋅4−y⋅46=
We use the power property to multiply terms with identical bases:
am⋅an=am+nWe apply the property for this problem:
42y⋅4−5⋅4−y⋅46=42y+(−5)+(−y)+6=42y−5−y+6We simplify the expression we got in the last step:
42y−5−y+6=4y+1When we add similar terms in the exponent.
Therefore, the correct answer is option c.