Please help! I don't know how I'd write the final anwesr.

Answer:
[tex]-5*4*a = -20*a[/tex] is the correct answer
Step-by-step explanation:
Square root of 16 = 4, and the square root of a^2 can be -a or +a, it says that a<0. so the answer is -20*a.
Hope this helps!