IBEW Solving Linear Equations 4 — Questions and Answers
Question 1: Solve for x: 9x = 63
- x = 7 (Correct answer)
- x = 9
- x = 54
- x = 72
Correct answer: x = 7
Divide both sides by 9: x = 63 ÷ 9 = 7.
Question 2: Two circuits carry currents that sum to 30 amps. If one carries 6 more amps than the other, how many amps does the smaller circuit carry?
- 12 amps (Correct answer)
- 18 amps
- 15 amps
- 6 amps
Correct answer: 12 amps
Let x = smaller; x + (x+6) = 30, so 2x = 24, x = 12 amps.
Question 3: Solve for x: 2x/5 = 8
- x = 20 (Correct answer)
- x = 16
- x = 4
- x = 40
Correct answer: x = 20
Multiply both sides by 5: 2x = 40, then divide by 2: x = 20.
Question 4: Solve for y: 4y - 3 = 2y + 7
- y = 5 (Correct answer)
- y = 2
- y = 4
- y = 10
Correct answer: y = 5
Subtract 2y: 2y - 3 = 7, add 3: 2y = 10, divide: y = 5.
Question 5: If 5(x - 1) = 20, what is x?
- x = 5 (Correct answer)
- x = 4
- x = 3
- x = 21
Correct answer: x = 5
Divide by 5: x - 1 = 4, then add 1: x = 5.
Question 6: A pipe runs 15 feet longer than half the total length of a trench. If the trench is 50 feet long, how long is the pipe?
- 40 feet (Correct answer)
- 25 feet
- 35 feet
- 32.5 feet
Correct answer: 40 feet
Pipe = 50/2 + 15 = 25 + 15 = 40 feet.
Question 7: Solve for x: -5x + 10 = -15
- x = 5 (Correct answer)
- x = -5
- x = 1
- x = -1
Correct answer: x = 5
Subtract 10: -5x = -25, then divide by -5: x = 5.
