To be a multiple of 4, 10 and 20 the number must be a multiple of their lowest common multiple.
lcm(4, 10, 20) = 20
What is required is a multiple of 20 between 61 and 107. The numbers 80 and 100 both satisfy the problem of being between 61 and 107 and being a multiple of 4, 10 and 20.
The number is 90.
It is: 80
90
90
98
80 meets the requirements.
90
It is: 80
Just 90
80
The number is 80
80 adn 100