I think the answer is a = 4.5
81 ÷ 6 ÷ 3 = 4.5
I hope this helps, have a wonderful day!
Answer:

Step-by-step explanation:
Given:

Let us assume that this equation is equal to 0.
Hence 
Now Solving the above equation we get,

Hence by solving the equation we get 
Answer:
a=-1
Step-by-step explanation:
2a-3=-5
2a=-5+3
2a=-2
a=-2/2
a=-1