The inhabitants of mars use the same mathematical operations that we do, namely + - ● ÷
They also use the operator ☻ that we do not know.
The following are true for any REAL numbers x and y:
x☻0 = x
x☻y = y☻x
(x+1)☻y = (x☻y)+y+1
What is the value of 12☻5?