━━━━━━━━━━━━━━━ ♡ ━━━━━━━━━━━━━━━
So the "back" of the arrow is on/above -20.
The arrow points to -12.
You added something to -20 to get to -12.
So the first number is -20. You added ? to get -12. -12 is the last number / the answer to the equation.
So the equation from what you have so far is -20 + ? = -12
You need to isolate the ? so that you know what it is.
So to get rid of the -20 (make it 0), you have to add 20. -20 plus 20 equals 0, which basically means it is gone. You also have to add 20 to -12. 20 plus -12 equals 8.
Now the equation is ? = 8.
So you know that the second number is 8.
The equation makes sense; -20 + 8 = -12.
━━━━━━━━━━━━━━━ ♡ ━━━━━━━━━━━━━━━