Name_________________________________________________________
7.5
Date __________
Practice A
In Exercises 1–3, solve the equation by cross multiplying. Check your solution(s).
1.
3
1

4x
x2
2.
4
6

x2
x2
3.
3
x5

x 1
x5
4. So far in baseball practice, you have pitched 47 strikes out of 61 pitches. Solve the
80
47  x
to find the number x of consecutive strikes you need to

100
61  x
pitch to raise your strike percentage to 80%.
equation
In Exercises 5 and 6, identify the least common denominator of the equation.
5.
x
2
5


x2
x
x
6.
3x
8
2


x5 x
x
In Exercises 7–12, solve the equation by using the LCD. Check your solution(s).
7.
4 2

 4
3
x
9.
x2
2x
3 
x3
x
10.
4
1
x 1


x5 x
x5
11.
8
x8
3 
x
x4
12.
12
3
3


x  2x
x2
x
8.
5
1
9


2x 4
2x
2
13. Describe and correct the error in the first step of solving the equation.
14. You can clean the gutters of your house in 5 hours. Working together, you and
your friend can clean the gutters in 3 hours. Let t be the time (in hours) your friend
would take to clean the gutters when working alone. Write and solve an equation
to find how long your friend would take to clean the gutters when working alone.
Hint: Work done  Work rate  Time
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All rights reserved.
Algebra 2
Resources by Chapter
247
Name _________________________________________________________ Date _________
7.5
Practice B
In Exercises 1–3, solve the equation by cross multiplying. Check your solution(s).
1.
3
5

x2
x2
2.
2
x3

x4
x 1
3.
x5
x2  5

4
x  4
4. So far in soccer practice, you have made 10 out of 32 goal attempts. Solve the
10  x
to find the number x of consecutive goals you need to
32  x
make to raise your goal average to 0.45.
equation 0.45 
In Exercises 5 and 6, identify the least common denominator of the equation.
5.
6
x
4


x3 x2
5
6.
6
2x
9


x  8 3x  2
4
In Exercises 7–12, solve the equation by using the LCD. Check your solution(s).
5
1
x 1


x6 x
x6
7.
3
1
7
 
4x 8
4x
9.
x4
4x
5 
x5
x
10.
16
8
4


x  4x
x4
x
x 1 1
2x  1


x2
x
x2
12.
4
4
1 
x
x2
11.
8.
2
13. Describe and correct the error in the first step of solving the equation.
14. You can kayak around a certain island in 3 hours. Kayaking together, you and
your friend can kayak around the island in 1.4 hours. Let t be the time (in hours)
your friend would take to kayak around the island when kayaking alone. Write and
solve an equation to find how long your friend would take to kayak around the
island when kayaking alone.
Hint: Work done  Work rate  Time
248 Algebra 2
Resources by Chapter
Copyright © Big Ideas Learning, LLC
All rights reserved.