When finding a decimal, you start at the end of the number, in your case 10, you want to go over as many zeros are there with the number you are trying to find the decimal to.
ill draw it out so youll maybe understand it better. I know its awful but it might help.
<span>B=89 lbs ANSWER: The mix contained 89 pounds of Type B coffee. CHECK: 167lbs-89lbs=78 lbs She used 78 pounds of Type A coffee. $4.35A+$5.70B=$846.60 $4.35(78)+$5.70(89)=$846.60 $339.30+$507.30=$846.60 $846.60=$846.60</span>
