.725 , .572 , .275, .2
You look at the first decimal place to see which is the greatest. 7 is greater than 5 and 2 so it's first. Then 5 is greater than 2 so it is next. For the last two numbers since 2 is the same value you look at the next decimal place. Since 7 is greater than 0 it comes next!
Each hour,
x makes b/6 bearings
y makes b/4 bearings
z makes b/3 bearings
Together, each hour, x, y and z together make
b/6+b/4+b/3=b(1/6+1/4+1/3)=b(2/12+3/12+4/12)=b(3/4)=3b/4 bearings.
Time to make b bearings =
b/(3b/4)=4/3 hours = 1 hour 20 minutes.
