i am trying to find/create a formula with the following information but have
seem to hit a wall i will try to explain

if b1 is greater than or equal to 20 than b2 is 25 or
b1 is greater than or equal to 15 but less than 20 b2 is 20 or
b1 is greater than or equal to 10 but less than 15 b2 is 15 or
b1 is greater than or equal to 2 but less than 10 b2 is 10 or
b1 is greater than or equal to 1 but less than 2 b2 is 5 or
b1 is less than 1 than b2 is 0

thanks for any ifo available