Solving Two-Step Equations

Show your work for each problem.

1.
What is the first step to solve ?
1. a)Add 7 to both sides
2. b)Multiply both sides by 2
3. c)Subtract 7 from both sides
4. d)Divide both sides by 2
Answer: Subtract 7 from both sides
In , we first subtract 7 from both sides to get , then divide by 2. Always undo addition/subtraction first!
2.
Solve for :
Answer: 5
→ → . Check: ✓
3.
Solve for :
Answer: 5
1. What do you add to both sides to undo the subtraction? 8
2. What is ? 20
3. Divide 20 by 4 to find x 5
4.
Solve for :
1. a)
2. b)
3. c)
4. d)
Answer:
→ → . Check: ✓
5.
Solve for :
Answer: 6
→ → . Check: ✓
6.
Solve for :
Answer: 15
1. What do you subtract from both sides? 4
2. What is ? 5
3. Multiply both sides by 3 to find x 15
7.
Solve for :
Answer: 7
→ → . Check: ✓
8.
Solve for :
Answer: 40
1. What do you add to both sides to undo the subtraction? 2
2. What is ? 8
3. What do you multiply both sides by to isolate x? 5
4. What is ? 40
9.
A phone plan costs 12 dollars per month plus a 30 dollar activation fee. If the total cost is 102 dollars, how many months is the plan?
1. a)9 months
2. b)8 months
3. c)6 months
4. d)7 months
Answer: 6 months
→ → months. Check: ✓
10.
A taxi charges 3 dollars as a base fare plus 2 dollars per kilometer. If the total fare is 19 dollars, how many kilometers was the ride?
Answer: 8
1. Write the equation. If = kilometers, what is the equation? 2k + 3 = 19
2. Subtract 3 from both sides. What is ? 16
3. Divide by 2 to find the kilometers 8
11.
Solve for :
Answer: -2
→ → . Check: ✓
12.
Solve for :
Answer: 2
1. Add 20 to both sides. What is ? 16
2. Divide 16 by 8 to find x 2
13.
Solve for :
1. a)
2. b)
3. c)
4. d)
Answer:
→ → . Check: ✓
14.
Solve for :
Answer: -8
→ → . Check: ✓
15.
The formula for converting Celsius to Fahrenheit is . If the temperature is 50°F, what is it in Celsius?
Answer: 10
1. Substitute 50 for F: . Subtract 32 from both sides. What is ? 18
2. To undo , multiply by . What is ? 10
16.
Solve for :
1. a)
2. b)
3. c)
4. d)
Answer:
→ → . Check: ✓