Let's represent the number with Y
Twice the number will be 2Y
12 is subtracted from it. That will be;
2Y-12
And it is equal to 8
2Y-12=8
-12 will go over the equality sign to become +12
2Y=8+12
2Y=20
Divide both sides by 2
Y=20/2
Y=10
The number is 10
Have a nice day