Marina has 2.5 lb of cashews. She puts 6 oz of cashews in a bag and gives them to her brother. What weight of cashews does Marina have left?

Question

It is a math workbook question from the Holt McDougal Mathmatics Course 2 Homework and Practice Workbook. 

Answer 1

The first step of this problem is recognizing that the issue is that there are two different units.  There are pounds and ounces.  So first, we need to get the units to be the same.

 

There are 16 oz / 1 lb, so I recommend converting the 2.5 lb to oz.

 

2.5 lb * 16 oz / 1 lb cancels the lb's and leaves 40 oz.  It's hard to show fractions in this format, but you'll see that there are lbs both on top and bottom, so they cancel and leave oz

 

Now, the issue is that she has 40 oz of cashews and gives away 6 oz.  This can be represented as:

 

40 oz - 6 oz = 34 oz remaining.

Answer 2

The important thing to know here is that a pound has 16 ounces in it.  So 2.5 pounds times 16 ounces per pound is 40 ounces of cashews.  Then she gives 6 away so she is left with 40 minus 6 which is 34 ounces.