If x,20,30 and 60 are in proportion then what is the value of x?

Are 5,10,30 and 60 in proportion ?

Are 30,40,45 and 60 in proportion?

Are 30,40,45 and 60 in proportion?

Are 5, 10, 20 and 30 in proportion ?

If 3, 8, x and 16 are in proportion the value of x is

Are 30, 40, 45 and 60 in proportion?

If x is subtracted from each of the numbers 20,37,54 and 105 then the numbers so obtained in this order are in proportion.What is the value of x ?

Are 40,30,60,45 in proportion?