Solving Equations by Adding or Subtracting Decimals

1
Solving Equations by Adding or Subtracting
Decimals
PRE-ALGEBRA LESSON 3-5
(For help, go to Skills Handbook page 730.)
Simplify. 1. 2.8 7.06 2. 0.65 1.8
3. 4.52 2.48 4. 3.7 0.62
Check Skills Youll Need
3-5
2
Solving Equations by Adding or Subtracting
Decimals
PRE-ALGEBRA LESSON 3-5
Solutions 1. 2.80 2. 0.65 7.06
1.80 9.86 2.45 3. 4.52 4. 3.70
2.48 0.62 2.04 3.08
3-5
3
Solving Equations by Adding or Subtracting
Decimals
PRE-ALGEBRA LESSON 3-5
Solve 6.8 p 9.7.
6.8 p 9.7
Quick Check
3-5
4
Solving Equations by Adding or Subtracting
Decimals
PRE-ALGEBRA LESSON 3-5
Ping has a board that is 14.5 ft long. She saws
off a piece that is 8.75 ft long. Use the diagram
below to find the length of the piece that is
left.
x 8.75 14.5
The length of the piece that is left is 5.75 ft.
Quick Check
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5
Solving Equations by Adding or Subtracting
Decimals
PRE-ALGEBRA LESSON 3-5
Solve 23.34 q 16.99.
23.34 q 16.99
Quick Check
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6
Solving Equations by Adding or Subtracting
Decimals
PRE-ALGEBRA LESSON 3-5
Quick Check
Alejandro wrote a check for 49.98. His new
account balance is 169.45. What was his previous
balance?
p 49.98 169.45
Alejandro had 219.43 in his account before he
wrote the check.
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7
Solving Equations by Adding or Subtracting
Decimals
PRE-ALGEBRA LESSON 3-5
Solve each equation. 1. a 10 7.9 2. 1.01
c 9 3. s (2.6) 1.6 4. 3.02 d
2.91 5. 23.7 13.3 g
2.1
7.99
1
0.11
37
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8
Solving Equations by Multiplying or Dividing
Decimals
PRE-ALGEBRA LESSON 3-6
Every day the school cafeteria uses about 85.8
gallons of milk. About how many days will it take
for the cafeteria to use the 250 gallons in the
refrigerator?
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Solving Equations by Multiplying or Dividing
Decimals
PRE-ALGEBRA LESSON 3-6
(continued)
85.8x 250
The school will take about 3 days to use 250
gallons of milk.
Quick Check
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10
Solving Equations by Multiplying or Dividing
Decimals
PRE-ALGEBRA LESSON 3-6
Solve 37.5 .
Quick Check
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11
Solving Equations by Multiplying or Dividing
Decimals
PRE-ALGEBRA LESSON 3-6
A little league player was at bat 15 times and
had a batting average of 0.133 (rounded to the
nearest thousandth). The batting average formula
is a , where a is the batting average, h is
the number of hits, and n is the number of times
at bat. Use the formula to find the number of
hits she made.
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12
Solving Equations by Multiplying or Dividing
Decimals
PRE-ALGEBRA LESSON 3-6
(continued)
The little league player made 2 hits.
Quick Check
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13
Solving Equations by Multiplying or Dividing
Decimals
PRE-ALGEBRA LESSON 3-6
Solve each equation. 1. 9b 30.6 2. 10.8
3. 2.45 0.7k 4. 240 5. y
(0.3) 146.7
3.4
27
t 3.7
3.5
888
44.01
3-6