Transcript 3 2

Solving Equations with Decimals.
Solve:
m + 4.6 = 9
m + 4.6 = 9
– 4.6 = – 4.6
m = 4.4
Subtract 4.6 from
both sides.
Solve:
x
= 15
1.2
x
= 1.2 • 15
1.2 •
1.2
x = 18
Multiply both sides by 1.2
Solving Equations with Fractions
Solve:
3
2
n+ =–
7
7
2 2
3 2
n– + =– –
7 7
7 7
n=–
5
7
2
Subtract
from both sides.
7
Solving Equations with Fractions
Solve:
5
5x
=
8
6
5
6
5
63
•
x= 8 •
5
6
5
4
3
x =
4
6
Multiply both sides by .
5
Simplify.
Solving Word Problems Using
Equations
Mr. Rios wants to prepare a dessert, but only
has 2 2 tablespoons of sugar. If each serving
3
of the dessert has 2 tablespoon of sugar, how
3
many servings can he make for the party?
Write an equation:
Total servings
s


Amount
needed
for each
dessert
2
3
=
=
Amount of
sugar
2
23
Now solve the equation:
s  2 = 22
3
3
3
2
3
2
3
Multiply both sides by
.
s 

=
2

2
3
2
3 2
8
3
s= 3  2
24
s = 6 , or 4 Simplify.
Mr. Rios can make 4 servings.
Problem Solving Application
The mechanic’s bill to repair Mr.
Wong’s car was $650. The mechanic
charges $45 an hour for labor, and
the parts that were used cost $443.
How many hours did the mechanic
work on the car?
Step #1
1
Understand the Problem
List the important
information:
The answer is the number of hours the
mechanic worked on the car.
• The parts cost $443.
• The labor cost $45 per hour.
• The total bill was $650.
Let h represent the hours the mechanic
worked.
Total bill =
Parts
+
Labor
650
=
443
+
45h
Step #2
2 Make a Plan
Think: First the variable is multiplied
by 45, and then 443 is added to the
result. Work backward to solve the
equation. Undo the operations in
reverse order: First subtract 443
from both sides of the equation, and
then divide both sides of the new
equation by 45.
Step #3
3 Solve
650 = 443 + 45h
–443 –443
207 =
207 = 45h
45
45
4.6 = h
Subtract to undo the addition.
45h
Divide to undo
multiplication.
The mechanic worked for 4.6 hours on Mr.
Wong’s car.