How would you solve this math problem

the number X is 20 percent of Y, which is 20 percent of Z, which is 20 percent of B, whose value is 100. What is the value of x?

The answer is .8 but i want to know HOW to do it.

Thank you all

B = 100

Z = 20% of B = .2 * B = .2 * 100 = 20

Y = 20% of Z = .2 * Z = .2 * 20 = 4

X = 20% of Y = .2 * Y = .2 * 4 = .8

Alternatively, 20% of 20% of 20% is 0.8%, and 0.8% of 100 is .8