The questions asks you to write a number in which the digit "5" is one-tenth the value of the number 5 in 89.547. You are looking for a number that is one-tenth of 0.5. Remember, one-tenth equals 1/10 which equals 0.1. One-tenth of 0.5 equals 0.1 multiplied by 0.5 which equals 0.05.
