Let x represent the number
Twice the number is 2 * x = 2x
4 times the number is 4 * x = 4x
We were told twice a number is 36 less than 4 times the number. This means that
2x = 4x - 36
By collecting like terms,
4x - 2x = 36
2x = 36
x = 36/2
x = 18
The number is 18