Download Lesson 7.1 - Crestwood Local Schools

Solving Two-Step Equations
PRE-ALGEBRA LESSON 7-1
Solve each equation.
a. 15 = 8 + n
n= 7
b. p – 19 = 4
p = 23
7-1
Solving Two-Step Equations
PRE-ALGEBRA LESSON 7-1
(For help, go to Lesson 2-5.)
Solve each equation.
1. 9 + k = 17
2. d – 10 = 1
4. x + 16 = 4
5. b + 6 = –4
3. y – 5 = –4
Check Skills You’ll Need
7-1
Solving Two-Step Equations
PRE-ALGEBRA LESSON 7-1
Solutions
9 + k = 17
–9 + 9 + k = –9 + 17
k=8
2.
d – 10 = 1
d – 10 + 10 = 1 + 10
d = 11
3.
y – 5 = –4
y – 5 + 5 = –4 + 5
y =1
4.
x + 16 = 4
x + 16 – 16 = 4 – 16
x = –12
5.
b + 6 = –4
b + 6 – 6 = –4 – 6
b = –10
1.
7-1
Solving Two-Step Equations
PRE-ALGEBRA LESSON 7-1
Solve 5v – 12 = 8.
5v – 12 = 8
5v – 12 + 12 = 8 + 12 Add 12 to each side.
5v = 20
Simplify.
5v 20
= 5
5
Divide each side by 5.
v=4
Simplify.
Check 5v – 12 = 8
5(4) – 12
8
Replace v with 4.
20 – 12
8
Multiply.
8=8
Simplify.
Quick Check
7-1
Solving Two-Step Equations
PRE-ALGEBRA LESSON 7-1
Solve 7 – 3b = 1.
7 – 3b = 1
–7 + 7 – 3b = –7 + 1
0 – 3b = –6
Add –7 to each side.
Simplify.
–3b = –6
0 – 3b = –3b.
–3b
–6
=
–3
–3
Divide each side by –3.
b=2
Simplify.
Quick Check
7-1
Solving Two-Step Equations
PRE-ALGEBRA LESSON 7-1
You borrow $350 to buy a bicycle. You agree to
pay $100 the first week, and then $25 each week until the
balance is paid off. To find how many weeks w it will take
you to pay for the bicycle, solve 100 + 25w = 350.
100 + 25w = 350
100 + 25w – 100 = 350 – 100 Subtract 100 from each side.
25w = 250
Simplify.
25w
250
=
25
25
Divide each side by 25.
w = 10
Simplify.
It will take you 10 weeks to pay for the bicycle.
7-1
Quick Check
Solving Two-Step Equations
PRE-ALGEBRA LESSON 7-1
Solve each equation.
1. 12x – 14 = 10
2.
r
+ 7 = –4
3
–33
2
q
3. 9 – w = 13
4. –22 – 5 = –15
–35
–4
5. 4d – 57 = 7
16
7-1