Update your skills. See page 414 XVI.
Addition and Subtraction Equations
with Fractions
Objective To apply the Subtraction Property of Equality to solve addition equations with
fractions • To apply the Addition Property of Equality to solve subtraction equations with fractions
Herman packages nails for a hardware company. He weighs
them instead of counting the individual nails. If the scale already
shows pound, what fraction of a pound of nails does he need
to make a -pound package?
To find the amount, write an addition equation, and apply the
Subtraction Property of Equality.
Let xthe fraction of a pound of nails needed.
Solve:x
x
x
x Express in simplest form.
Check:x
Substitute for x.
Rename as fractions with a common denominator, then add.
Tr u e
So Herman needs pound of nails to make a -pound package.
To solve an addition equation with signed fractions, follow the
same rules as you use to add and subtract integers.
Solve:n()
n()() ()
n
n
n
n
Simplify. Divide the numerator
and denominator by their GCF, 3.
Use the Subtraction Principle.
Add.
3
8
3
16
3
16
9
16
3
8
3
5
9 3
15 3
9
15
3
15
6
15
6
15
6
15
3
15
6
15
6
15
3
15
3
16
9
16
9
16
9
16
3
16
6
16
?^9
16
?^9
16
3
8
9
16
3
16
9
16
6
16 Rename as fractions with a common
denominator, then subtract.
3
8
3
8
9
16
3
8
3
8
9
16
&KDSWHU
5-14
Remember:
Subtraction Property of Equality
If a b, then a c b c.
Subtract from both sides
to isolate x.
3
8
Subtract from both
sides to isolate n.
6
15
Check:n()
()
()
153 153 Tr u e
3
15
(^6) ?
15
9
15
3
15
(^6) ?
15
3
5
3
15
6
15