Sara Bredbenner and Blake DeYoung are teammates at a discount? store; their new job is assembling swing sets for customers. Assembly of a swing set has a learning rate of 70%. They forgot to time their effort on the first swing? set, but spent 6 hours on the second set. They have 6 more sets to do. Determine approximately how much time will be? (was) required? for:
a) The 1st unit = ____ hours?
b) The 8th unit = ____ hours?
c) The total amount of hours to build 8 units = ____ hours?