You order from a catalog the following office supplies: 10 boxes of paper, each box is 6 pounds and 36 boxes of pens, each box weighs 12 ounces. shipping charges are $12.00 for the first 20 pounds, $10.00 for the next 30 pounds, $0.50 per pound for the next 50 pounds. what will the shipping charges be?

So, you start of with 10 boxes, which are 6 pounds each. 10 x 6=60. So the boxes of paper are 60 pounds in total. then you see how much the boxes of pens weigh. There are 36 boxes of pens that weigh 12 ounces each. 36 x 12 = 432 ounces total. 16 ounces = 1 pound. So you must divide the total amount of ounces, 432 by 16 which gets you 27. that means that the 432 ounces equals 27 pounds. Now, you have to add up everything. 60 pounds for the paper and 27 pounds for the pens: 87 pounds total. 

Shipping charges are $12.00 for the first 20 pounds, $10.00 for the next 30 pounds. Then you have a left over 37 pounds to find the charges of. You then multiply 37 by .50. It gets you $18.50.

Finally you add up all of the charges and you get $40.50.

By my calculations the charges would be $457.00