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When we subtract rational numbers we are finding the difference between those two number on a number line.

For example we need to look at how far we go from -6 to get to 4.

Because we move to the right on the number line the distance is positive!

4 6

We can use this strategy:We can Add the opposite of the decimal!

-2.3 – (-3.9) =

-2.3 – (-3.9) = = -2.3 + (+3.9)

= -2.3 + 3.9 = 1.6

1

2

11

3Similar steps to adding fractions. Find the lowest common denominator.

Change both fractions to equivalent fractions. Add the numerators.

1

2

11

3

X 3

X 3

X 2

X 2

3

6

22

6

3 22

6

19

6

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Strategy – change the Mixed Number to an IMPROPER fraction and follow from there.

5

4 3

1

5

Page 119-121 #4, 5 all, 7bdf,

9f, 10, 11, 13cd, 15abc

The following slides are not a part of the current notes for Section 3.3

Strategy ONE- is to place the number being subtracted on a number line and follow from there

Strategy TWO – is to change the Mixed Number to an IMPROPER fraction and follow from there.

5

4 3

1

5

5

4 3

1

5

It is important to remember that when we are subtracting rational numbers to use equivalent fractions. These are numbers that have the same number of pieces.

Think ½ and 1/8 - in order to make them equivalent they both must be out of 8ths

is And

1/2 is the same as 4/8 so: 4

81

83

8

Math Makes Sense – SEE IT ( link page 115)