September 25, 2012
Lesson 3.3
Problems With Two Or More Unknowns
To solve problems with two or more unknowns
1. Determine which unknown will be represented
by a variable.
2. Use one of the relationships to describe the other
unknown(s) in terms of the variable.
3. Use the other relationship to write an equation.
4. Solve the equation.
Page 206 #6
The weight of a truck is 800 pounds more than the
weight of a car. If the weight of the car is
represented by x pounds,
a) Represent the weight of the truck in terms of x.
b) Write and solve an equation if the sum of the
weights of the two vehicles is 4550 pounds.
1
September 25, 2012
Page 207 #22
The greater of two numbers is 4 more than three
times the lesser number. If the sum of the two
numbers is 32, find the numbers.
Use a variable to represent one of the numbers.
Use n to represent the smaller number.
Represent the other number using the same
variable using information in the first sentence.
The larger number is 4 + 3n.
4+3(7)=25
Write an equation using the information in the
second sentence.
n + 4 + 3n = 32
4n + 4 = 32
4n = 28
n=7
Solve the equation.
Check to see if your answers fit the question.
7+25=32
Write out your answer.
The two numbers are 7 and 25.
2
September 25, 2012
Page 208 #36
The length of a rectangular room is 8 feet more the
the width, and the perimeter is 76 feet. What are
the dimensions of the room?
Represent the dimensions using a single variable.
W
P = 2L + 2W
W+8
What are supplementary angles? Angle pairs whose sum is 180°.
What are complementary angles? Angle pairs whose sum is 90°.
Page 209 #46
Two angles are supplementary. If the measure of
one angle is 44° more than the other angle, find the
measures of the two angles.
3
September 25, 2012
Consecutive Integer Problems:
n, n + 1, n + 2, ... name consecutive integers.
n, n + 2, n + 4, ... name consecutive even or
odd integers depending on the value of n.
Page 209 #54
The sum of two consecutive integers is 123. What
are the integers?
Page 210 #68
Find three consecutive odd integers such that the
sum of three times the smallest integer and twice
the largest integer is seven more than four times
the middle integer.
4
September 25, 2012
Using a table to solve a word problem.
A vending machine has 12 oz. and 16 oz. drinks. The 12 oz.
drinks are $0.50 and the 16 oz. drinks are $1.00. If 3600
total drinks were sold in one month and the total sales were
$2225, how many of each size drink were sold?
Categories
Value of each
Number of items
Total amount
12 oz.
.50
n
.5n
16 oz.
1.00
3600 - n
1(3600 - n)
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September 25, 2012
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September 25, 2012
Categories
Value of each
Number of items
Total amount
7
September 25, 2012
8